Unit 11 — End of Topic Tests (reviewer copy: all keys and model answers visible)

[
 {
  "value": "NH₄⁺",
  "misconception": "you wrote the ammonium ion — NH₄⁺ is the 1+ ion; the base ammonia is the neutral compound NH₃",
  "feedback": "This answer is wrong — you wrote the ammonium ion — NH₄⁺ is the 1+ ion; the base ammonia is the neutral compound NH₃"
 },
 {
  "value": "HNO₃",
  "misconception": "you recalled the other nitrogen compound — HNO₃ is nitric acid; ammonia is NH₃",
  "feedback": "This answer is wrong — you recalled the other nitrogen compound — HNO₃ is nitric acid; ammonia is NH₃"
 },
 {
  "value": "NH₂",
  "misconception": "you dropped a hydrogen — ammonia carries three hydrogens: NH₃",
  "feedback": "This answer is wrong — you dropped a hydrogen — ammonia carries three hydrogens: NH₃"
 }
]

{
 "keyExplanation": "Ammonia is NH₃ — one nitrogen, three hydrogens, no metal, no OH. It is the base in many glass cleaners.",
 "anticipatedWrong": [
  {
   "value": "NH₄⁺",
   "misconception": "you wrote the ammonium ion — NH₄⁺ is the 1+ ion; the base ammonia is the neutral compound NH₃",
   "feedback": "This answer is wrong — you wrote the ammonium ion — NH₄⁺ is the 1+ ion; the base ammonia is the neutral compound NH₃"
  },
  {
   "value": "HNO₃",
   "misconception": "you recalled the other nitrogen compound — HNO₃ is nitric acid; ammonia is NH₃",
   "feedback": "This answer is wrong — you recalled the other nitrogen compound — HNO₃ is nitric acid; ammonia is NH₃"
  },
  {
   "value": "NH₂",
   "misconception": "you dropped a hydrogen — ammonia carries three hydrogens: NH₃",
   "feedback": "This answer is wrong — you dropped a hydrogen — ammonia carries three hydrogens: NH₃"
  }
 ]
}

[
 {
  "value": "H₂S",
  "misconception": "you added two hydrogens — one accepted proton adds exactly one H, giving HS⁻",
  "feedback": "This answer is wrong — you added two hydrogens — one accepted proton adds exactly one H, giving HS⁻"
 },
 {
  "value": "HS²⁻",
  "misconception": "you kept the 2− charge — adding the 1+ proton raises the charge from 2− to 1−",
  "feedback": "This answer is wrong — you kept the 2− charge — adding the 1+ proton raises the charge from 2− to 1−"
 },
 {
  "value": "HS",
  "misconception": "you dropped the charge — the 2− plus the 1+ leaves 1−: HS⁻",
  "feedback": "This answer is wrong — you dropped the charge — the 2− plus the 1+ leaves 1−: HS⁻"
 }
]

{
 "keyExplanation": "Accepting an H⁺ grows the formula by one H and raises the charge by one. S²⁻ + H⁺ → HS⁻: two minuses plus one plus leaves a single 1− charge.",
 "anticipatedWrong": [
  {
   "value": "H₂S",
   "misconception": "you added two hydrogens — one accepted proton adds exactly one H, giving HS⁻",
   "feedback": "This answer is wrong — you added two hydrogens — one accepted proton adds exactly one H, giving HS⁻"
  },
  {
   "value": "HS²⁻",
   "misconception": "you kept the 2− charge — adding the 1+ proton raises the charge from 2− to 1−",
   "feedback": "This answer is wrong — you kept the 2− charge — adding the 1+ proton raises the charge from 2− to 1−"
  },
  {
   "value": "HS",
   "misconception": "you dropped the charge — the 2− plus the 1+ leaves 1−: HS⁻",
   "feedback": "This answer is wrong — you dropped the charge — the 2− plus the 1+ leaves 1−: HS⁻"
  }
 ]
}

[
 {
  "value": "chromous acid",
  "misconception": "you reversed the suffix — -ate points to -ic: chromATE gives chromIC acid",
  "feedback": "This answer is wrong — you reversed the suffix — -ate points to -ic: chromATE gives chromIC acid"
 },
 {
  "value": "hydrochromic acid",
  "misconception": "you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it",
  "feedback": "This answer is wrong — you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it"
 },
 {
  "value": "chromate acid",
  "misconception": "you kept the ion's name — the -ate ending converts to -ic acid in the acid's name",
  "feedback": "This answer is wrong — you kept the ion's name — the -ate ending converts to -ic acid in the acid's name"
 }
]

{
 "keyExplanation": "The ion's name ends in -ate, so the acid's name ends in -ic acid: chromate gives chromic acid. No hydro- prefix ever appears on an oxyacid's name.",
 "anticipatedWrong": [
  {
   "value": "chromous acid",
   "misconception": "you reversed the suffix — -ate points to -ic: chromATE gives chromIC acid",
   "feedback": "This answer is wrong — you reversed the suffix — -ate points to -ic: chromATE gives chromIC acid"
  },
  {
   "value": "hydrochromic acid",
   "misconception": "you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it",
   "feedback": "This answer is wrong — you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it"
  },
  {
   "value": "chromate acid",
   "misconception": "you kept the ion's name — the -ate ending converts to -ic acid in the acid's name",
   "feedback": "This answer is wrong — you kept the ion's name — the -ate ending converts to -ic acid in the acid's name"
  }
 ]
}

[
 {
  "value": "magnesium dihydroxide",
  "misconception": "you counted the hydroxides into the name — ionic names carry no counting prefixes",
  "feedback": "This answer is wrong — you counted the hydroxides into the name — ionic names carry no counting prefixes"
 },
 {
  "value": "manganese hydroxide",
  "misconception": "you mixed up magnesium and manganese — Mg is magnesium",
  "feedback": "This answer is wrong — you mixed up magnesium and manganese — Mg is magnesium"
 },
 {
  "value": "magnesium(II) hydroxide",
  "misconception": "you added a Roman numeral — magnesium forms only 2+, so no numeral is needed",
  "feedback": "This answer is wrong — you added a Roman numeral — magnesium forms only 2+, so no numeral is needed"
 }
]

{
 "keyExplanation": "Metal: magnesium. Ion: hydroxide. Mg(OH)₂ is magnesium hydroxide — the subscript 2 plays no part in the name.",
 "anticipatedWrong": [
  {
   "value": "magnesium dihydroxide",
   "misconception": "you counted the hydroxides into the name — ionic names carry no counting prefixes",
   "feedback": "This answer is wrong — you counted the hydroxides into the name — ionic names carry no counting prefixes"
  },
  {
   "value": "manganese hydroxide",
   "misconception": "you mixed up magnesium and manganese — Mg is magnesium",
   "feedback": "This answer is wrong — you mixed up magnesium and manganese — Mg is magnesium"
  },
  {
   "value": "magnesium(II) hydroxide",
   "misconception": "you added a Roman numeral — magnesium forms only 2+, so no numeral is needed",
   "feedback": "This answer is wrong — you added a Roman numeral — magnesium forms only 2+, so no numeral is needed"
  }
 ]
}

[
 {
  "value": "HClO₂",
  "misconception": "you reversed -ic to the wrong ion — -ic acid points back to the -ATE ion, chlorate, ClO₃⁻",
  "feedback": "This answer is wrong — you reversed -ic to the wrong ion — -ic acid points back to the -ATE ion, chlorate, ClO₃⁻"
 },
 {
  "value": "H₂ClO₃",
  "misconception": "you doubled the hydrogen — chlorate's 1− charge needs only one H",
  "feedback": "This answer is wrong — you doubled the hydrogen — chlorate's 1− charge needs only one H"
 },
 {
  "value": "HCl",
  "misconception": "you dropped the oxygens — chloric acid is an oxyacid; HCl is hydrochloric, the binary acid",
  "feedback": "This answer is wrong — you dropped the oxygens — chloric acid is an oxyacid; HCl is hydrochloric, the binary acid"
 }
]

{
 "keyExplanation": "-ic points back to the -ate ion: chlorate, ClO₃⁻. A 1− charge takes one H, so chloric acid is HClO₃.",
 "anticipatedWrong": [
  {
   "value": "HClO₂",
   "misconception": "you reversed -ic to the wrong ion — -ic acid points back to the -ATE ion, chlorate, ClO₃⁻",
   "feedback": "This answer is wrong — you reversed -ic to the wrong ion — -ic acid points back to the -ATE ion, chlorate, ClO₃⁻"
  },
  {
   "value": "H₂ClO₃",
   "misconception": "you doubled the hydrogen — chlorate's 1− charge needs only one H",
   "feedback": "This answer is wrong — you doubled the hydrogen — chlorate's 1− charge needs only one H"
  },
  {
   "value": "HCl",
   "misconception": "you dropped the oxygens — chloric acid is an oxyacid; HCl is hydrochloric, the binary acid",
   "feedback": "This answer is wrong — you dropped the oxygens — chloric acid is an oxyacid; HCl is hydrochloric, the binary acid"
  }
 ]
}

[
 {
  "value": "Na(OH)₂",
  "misconception": "you gave sodium a 2+ charge — Na⁺ is 1+, so one OH⁻ balances it: NaOH",
  "feedback": "This answer is wrong — you gave sodium a 2+ charge — Na⁺ is 1+, so one OH⁻ balances it: NaOH"
 },
 {
  "value": "NaO",
  "misconception": "you dropped the hydrogen — the hydroxide unit is OH, so the formula is NaOH",
  "feedback": "This answer is wrong — you dropped the hydrogen — the hydroxide unit is OH, so the formula is NaOH"
 },
 {
  "value": "NaOH₂",
  "misconception": "you doubled the hydrogen — one OH unit carries one H: NaOH",
  "feedback": "This answer is wrong — you doubled the hydrogen — one OH unit carries one H: NaOH"
 }
]

{
 "keyExplanation": "Sodium hydroxide is NaOH — one Na⁺ balanced by one OH⁻. It is the drain-cleaner base on the roster.",
 "anticipatedWrong": [
  {
   "value": "Na(OH)₂",
   "misconception": "you gave sodium a 2+ charge — Na⁺ is 1+, so one OH⁻ balances it: NaOH",
   "feedback": "This answer is wrong — you gave sodium a 2+ charge — Na⁺ is 1+, so one OH⁻ balances it: NaOH"
  },
  {
   "value": "NaO",
   "misconception": "you dropped the hydrogen — the hydroxide unit is OH, so the formula is NaOH",
   "feedback": "This answer is wrong — you dropped the hydrogen — the hydroxide unit is OH, so the formula is NaOH"
  },
  {
   "value": "NaOH₂",
   "misconception": "you doubled the hydrogen — one OH unit carries one H: NaOH",
   "feedback": "This answer is wrong — you doubled the hydrogen — one OH unit carries one H: NaOH"
  }
 ]
}

[
 {
  "value": "H₂Se",
  "misconception": "you added two hydrogens — accepting ONE H⁺ adds exactly one H: HSe⁻",
  "feedback": "This answer is wrong — you added two hydrogens — accepting ONE H⁺ adds exactly one H: HSe⁻"
 },
 {
  "value": "HSe²⁻",
  "misconception": "you added the H but kept the charge — gaining an H⁺ raises the charge by one, from 2− to 1−",
  "feedback": "This answer is wrong — you added the H but kept the charge — gaining an H⁺ raises the charge by one, from 2− to 1−"
 },
 {
  "value": "Se⁻",
  "misconception": "you raised the charge without adding the H — the formula grows by one H: HSe⁻",
  "feedback": "This answer is wrong — you raised the charge without adding the H — the formula grows by one H: HSe⁻"
 }
]

{
 "keyExplanation": "Accepting an H⁺ grows the formula by one H and raises the charge by one: Se²⁻ (2−) becomes HSe⁻ (1−).",
 "anticipatedWrong": [
  {
   "value": "H₂Se",
   "misconception": "you added two hydrogens — accepting ONE H⁺ adds exactly one H: HSe⁻",
   "feedback": "This answer is wrong — you added two hydrogens — accepting ONE H⁺ adds exactly one H: HSe⁻"
  },
  {
   "value": "HSe²⁻",
   "misconception": "you added the H but kept the charge — gaining an H⁺ raises the charge by one, from 2− to 1−",
   "feedback": "This answer is wrong — you added the H but kept the charge — gaining an H⁺ raises the charge by one, from 2− to 1−"
  },
  {
   "value": "Se⁻",
   "misconception": "you raised the charge without adding the H — the formula grows by one H: HSe⁻",
   "feedback": "This answer is wrong — you raised the charge without adding the H — the formula grows by one H: HSe⁻"
  }
 ]
}

[
 {
  "value": "chloric acid",
  "misconception": "you used the -ate rule — chlorITE takes -ous acid",
  "feedback": "This answer is wrong — you used the -ate rule — chlorITE takes -ous acid"
 },
 {
  "value": "hydrochlorous acid",
  "misconception": "you added hydro- — that prefix belongs to binary acids only",
  "feedback": "This answer is wrong — you added hydro- — that prefix belongs to binary acids only"
 },
 {
  "value": "chlorite acid",
  "misconception": "you left the ion's name unchanged — the -ite ending must switch to -ous",
  "feedback": "This answer is wrong — you left the ion's name unchanged — the -ite ending must switch to -ous"
 }
]

{
 "keyExplanation": "The ion is chlorite, ending in -ite, and -ite becomes -ous acid: chlorite → chlorous. HClO₂ is chlorous acid.",
 "anticipatedWrong": [
  {
   "value": "chloric acid",
   "misconception": "you used the -ate rule — chlorITE takes -ous acid",
   "feedback": "This answer is wrong — you used the -ate rule — chlorITE takes -ous acid"
  },
  {
   "value": "hydrochlorous acid",
   "misconception": "you added hydro- — that prefix belongs to binary acids only",
   "feedback": "This answer is wrong — you added hydro- — that prefix belongs to binary acids only"
  },
  {
   "value": "chlorite acid",
   "misconception": "you left the ion's name unchanged — the -ite ending must switch to -ous",
   "feedback": "This answer is wrong — you left the ion's name unchanged — the -ite ending must switch to -ous"
  }
 ]
}

[
 {
  "value": "rubidium oxide",
  "misconception": "you dropped the hydrogen — the ion is hydroxide, OH⁻: rubidium hydroxide",
  "feedback": "This answer is wrong — you dropped the hydrogen — the ion is hydroxide, OH⁻: rubidium hydroxide"
 },
 {
  "value": "rubidium hydride",
  "misconception": "you named the wrong ion — OH⁻ is hydroxide; hydride is the ion H⁻",
  "feedback": "This answer is wrong — you named the wrong ion — OH⁻ is hydroxide; hydride is the ion H⁻"
 },
 {
  "value": "hydrorubidic acid",
  "misconception": "you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide",
  "feedback": "This answer is wrong — you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide"
 }
]

{
 "keyExplanation": "A metal hydroxide takes its ordinary ionic name: metal name + hydroxide. RbOH is rubidium hydroxide.",
 "anticipatedWrong": [
  {
   "value": "rubidium oxide",
   "misconception": "you dropped the hydrogen — the ion is hydroxide, OH⁻: rubidium hydroxide",
   "feedback": "This answer is wrong — you dropped the hydrogen — the ion is hydroxide, OH⁻: rubidium hydroxide"
  },
  {
   "value": "rubidium hydride",
   "misconception": "you named the wrong ion — OH⁻ is hydroxide; hydride is the ion H⁻",
   "feedback": "This answer is wrong — you named the wrong ion — OH⁻ is hydroxide; hydride is the ion H⁻"
  },
  {
   "value": "hydrorubidic acid",
   "misconception": "you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide",
   "feedback": "This answer is wrong — you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide"
  }
 ]
}

[
 {
  "value": "H₂TeO₄",
  "misconception": "you reversed -ous to the wrong ion — -ous acid points back to the -ITE ion, tellurite, TeO₃²⁻; TeO₄²⁻ is tellurate",
  "feedback": "This answer is wrong — you reversed -ous to the wrong ion — -ous acid points back to the -ITE ion, tellurite, TeO₃²⁻; TeO₄²⁻ is tellurate"
 },
 {
  "value": "HTeO₃",
  "misconception": "you added a single H — tellurite's 2− charge takes two",
  "feedback": "This answer is wrong — you added a single H — tellurite's 2− charge takes two"
 },
 {
  "value": "H₃TeO₃",
  "misconception": "you overshot the H count — match it to the charge number, 2",
  "feedback": "This answer is wrong — you overshot the H count — match it to the charge number, 2"
 }
]

{
 "keyExplanation": "-ous points back to the -ite ion: tellurite, TeO₃²⁻. A 2− charge takes two H, so tellurous acid is H₂TeO₃.",
 "anticipatedWrong": [
  {
   "value": "H₂TeO₄",
   "misconception": "you reversed -ous to the wrong ion — -ous acid points back to the -ITE ion, tellurite, TeO₃²⁻; TeO₄²⁻ is tellurate",
   "feedback": "This answer is wrong — you reversed -ous to the wrong ion — -ous acid points back to the -ITE ion, tellurite, TeO₃²⁻; TeO₄²⁻ is tellurate"
  },
  {
   "value": "HTeO₃",
   "misconception": "you added a single H — tellurite's 2− charge takes two",
   "feedback": "This answer is wrong — you added a single H — tellurite's 2− charge takes two"
  },
  {
   "value": "H₃TeO₃",
   "misconception": "you overshot the H count — match it to the charge number, 2",
   "feedback": "This answer is wrong — you overshot the H count — match it to the charge number, 2"
  }
 ]
}

[
 {
  "value": "K(OH)₂",
  "misconception": "you gave potassium a 2+ charge — K⁺ is 1+, so one OH⁻ balances it: KOH",
  "feedback": "This answer is wrong — you gave potassium a 2+ charge — K⁺ is 1+, so one OH⁻ balances it: KOH"
 },
 {
  "value": "KH",
  "misconception": "you dropped the oxygen — the hydroxide unit is OH: KOH",
  "feedback": "This answer is wrong — you dropped the oxygen — the hydroxide unit is OH: KOH"
 },
 {
  "value": "NaOH",
  "misconception": "you wrote the sodium base — potassium hydroxide starts from potassium: KOH",
  "feedback": "This answer is wrong — you wrote the sodium base — potassium hydroxide starts from potassium: KOH"
 }
]

{
 "keyExplanation": "Potassium hydroxide is KOH — one K⁺ balanced by one OH⁻. It is the base used to make liquid soaps.",
 "anticipatedWrong": [
  {
   "value": "K(OH)₂",
   "misconception": "you gave potassium a 2+ charge — K⁺ is 1+, so one OH⁻ balances it: KOH",
   "feedback": "This answer is wrong — you gave potassium a 2+ charge — K⁺ is 1+, so one OH⁻ balances it: KOH"
  },
  {
   "value": "KH",
   "misconception": "you dropped the oxygen — the hydroxide unit is OH: KOH",
   "feedback": "This answer is wrong — you dropped the oxygen — the hydroxide unit is OH: KOH"
  },
  {
   "value": "NaOH",
   "misconception": "you wrote the sodium base — potassium hydroxide starts from potassium: KOH",
   "feedback": "This answer is wrong — you wrote the sodium base — potassium hydroxide starts from potassium: KOH"
  }
 ]
}

[
 {
  "value": "H₂NO₂",
  "misconception": "you added two hydrogens — one H⁺ adds exactly one H: HNO₂",
  "feedback": "This answer is wrong — you added two hydrogens — one H⁺ adds exactly one H: HNO₂"
 },
 {
  "value": "HNO₂⁻",
  "misconception": "you kept the 1− charge — gaining an H⁺ raises it by one, to neutral: HNO₂",
  "feedback": "This answer is wrong — you kept the 1− charge — gaining an H⁺ raises it by one, to neutral: HNO₂"
 },
 {
  "value": "NO₃⁻",
  "misconception": "you added an oxygen instead of a hydrogen — accepting H⁺ changes the H count, not the O count",
  "feedback": "This answer is wrong — you added an oxygen instead of a hydrogen — accepting H⁺ changes the H count, not the O count"
 }
]

{
 "keyExplanation": "Accepting an H⁺ grows the formula by one H and raises the charge by one: NO₂⁻ (1−) becomes the neutral particle HNO₂.",
 "anticipatedWrong": [
  {
   "value": "H₂NO₂",
   "misconception": "you added two hydrogens — one H⁺ adds exactly one H: HNO₂",
   "feedback": "This answer is wrong — you added two hydrogens — one H⁺ adds exactly one H: HNO₂"
  },
  {
   "value": "HNO₂⁻",
   "misconception": "you kept the 1− charge — gaining an H⁺ raises it by one, to neutral: HNO₂",
   "feedback": "This answer is wrong — you kept the 1− charge — gaining an H⁺ raises it by one, to neutral: HNO₂"
  },
  {
   "value": "NO₃⁻",
   "misconception": "you added an oxygen instead of a hydrogen — accepting H⁺ changes the H count, not the O count",
   "feedback": "This answer is wrong — you added an oxygen instead of a hydrogen — accepting H⁺ changes the H count, not the O count"
  }
 ]
}

[
 {
  "value": "borous acid",
  "misconception": "you reversed the suffix — -ate points to -ic: borATE gives borIC acid",
  "feedback": "This answer is wrong — you reversed the suffix — -ate points to -ic: borATE gives borIC acid"
 },
 {
  "value": "hydroboric acid",
  "misconception": "you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it",
  "feedback": "This answer is wrong — you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it"
 },
 {
  "value": "triboric acid",
  "misconception": "you counted the hydrogens into the name — subscripts play no part in an oxyacid's name",
  "feedback": "This answer is wrong — you counted the hydrogens into the name — subscripts play no part in an oxyacid's name"
 }
]

{
 "keyExplanation": "The ion's name ends in -ate, so the acid's name ends in -ic acid: borate gives boric acid. The hydrogen count plays no part in the name.",
 "anticipatedWrong": [
  {
   "value": "borous acid",
   "misconception": "you reversed the suffix — -ate points to -ic: borATE gives borIC acid",
   "feedback": "This answer is wrong — you reversed the suffix — -ate points to -ic: borATE gives borIC acid"
  },
  {
   "value": "hydroboric acid",
   "misconception": "you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it",
   "feedback": "This answer is wrong — you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it"
  },
  {
   "value": "triboric acid",
   "misconception": "you counted the hydrogens into the name — subscripts play no part in an oxyacid's name",
   "feedback": "This answer is wrong — you counted the hydrogens into the name — subscripts play no part in an oxyacid's name"
  }
 ]
}

[
 {
  "value": "cesium oxide",
  "misconception": "you dropped the hydrogen — the ion is hydroxide, OH⁻: cesium hydroxide",
  "feedback": "This answer is wrong — you dropped the hydrogen — the ion is hydroxide, OH⁻: cesium hydroxide"
 },
 {
  "value": "cesium hydride",
  "misconception": "you named the wrong ion — OH⁻ is hydroxide; hydride is the ion H⁻",
  "feedback": "This answer is wrong — you named the wrong ion — OH⁻ is hydroxide; hydride is the ion H⁻"
 },
 {
  "value": "hydrocesic acid",
  "misconception": "you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide",
  "feedback": "This answer is wrong — you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide"
 }
]

{
 "keyExplanation": "A metal hydroxide takes its ordinary ionic name: metal name + hydroxide. CsOH is cesium hydroxide.",
 "anticipatedWrong": [
  {
   "value": "cesium oxide",
   "misconception": "you dropped the hydrogen — the ion is hydroxide, OH⁻: cesium hydroxide",
   "feedback": "This answer is wrong — you dropped the hydrogen — the ion is hydroxide, OH⁻: cesium hydroxide"
  },
  {
   "value": "cesium hydride",
   "misconception": "you named the wrong ion — OH⁻ is hydroxide; hydride is the ion H⁻",
   "feedback": "This answer is wrong — you named the wrong ion — OH⁻ is hydroxide; hydride is the ion H⁻"
  },
  {
   "value": "hydrocesic acid",
   "misconception": "you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide",
   "feedback": "This answer is wrong — you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide"
  }
 ]
}

[
 {
  "value": "H₃AsO₃",
  "misconception": "you swapped in the -ite ion — -ic acid points back to arsenATE, AsO₄³⁻",
  "feedback": "This answer is wrong — you swapped in the -ite ion — -ic acid points back to arsenATE, AsO₄³⁻"
 },
 {
  "value": "HAsO₄",
  "misconception": "you added a single H — arsenate's 3− charge takes three",
  "feedback": "This answer is wrong — you added a single H — arsenate's 3− charge takes three"
 },
 {
  "value": "H₂AsO₄",
  "misconception": "you stopped at two hydrogens — match the H count to the charge number, 3",
  "feedback": "This answer is wrong — you stopped at two hydrogens — match the H count to the charge number, 3"
 }
]

{
 "keyExplanation": "-ic points back to the -ate ion: arsenate, AsO₄³⁻. A 3− charge takes three H, so arsenic acid is H₃AsO₄.",
 "anticipatedWrong": [
  {
   "value": "H₃AsO₃",
   "misconception": "you swapped in the -ite ion — -ic acid points back to arsenATE, AsO₄³⁻",
   "feedback": "This answer is wrong — you swapped in the -ite ion — -ic acid points back to arsenATE, AsO₄³⁻"
  },
  {
   "value": "HAsO₄",
   "misconception": "you added a single H — arsenate's 3− charge takes three",
   "feedback": "This answer is wrong — you added a single H — arsenate's 3− charge takes three"
  },
  {
   "value": "H₂AsO₄",
   "misconception": "you stopped at two hydrogens — match the H count to the charge number, 3",
   "feedback": "This answer is wrong — you stopped at two hydrogens — match the H count to the charge number, 3"
  }
 ]
}

[
 {
  "value": "CaOH",
  "misconception": "you dropped one hydroxide — calcium's 2+ charge takes two OH units: Ca(OH)₂",
  "feedback": "This answer is wrong — you dropped one hydroxide — calcium's 2+ charge takes two OH units: Ca(OH)₂"
 },
 {
  "value": "CaOH₂",
  "misconception": "you dropped the parentheses — without them the 2 counts only the hydrogen; two whole OH units are written Ca(OH)₂",
  "feedback": "This answer is wrong — you dropped the parentheses — without them the 2 counts only the hydrogen; two whole OH units are written Ca(OH)₂"
 },
 {
  "value": "Ca₂OH",
  "misconception": "you moved the 2 onto the calcium — one Ca²⁺ takes two OH⁻: Ca(OH)₂",
  "feedback": "This answer is wrong — you moved the 2 onto the calcium — one Ca²⁺ takes two OH⁻: Ca(OH)₂"
 }
]

{
 "keyExplanation": "Calcium hydroxide is Ca(OH)₂ — calcium's 2+ charge takes two hydroxide units, written with parentheses. It is sold as slaked lime for treating overly acidic soil.",
 "anticipatedWrong": [
  {
   "value": "CaOH",
   "misconception": "you dropped one hydroxide — calcium's 2+ charge takes two OH units: Ca(OH)₂",
   "feedback": "This answer is wrong — you dropped one hydroxide — calcium's 2+ charge takes two OH units: Ca(OH)₂"
  },
  {
   "value": "CaOH₂",
   "misconception": "you dropped the parentheses — without them the 2 counts only the hydrogen; two whole OH units are written Ca(OH)₂",
   "feedback": "This answer is wrong — you dropped the parentheses — without them the 2 counts only the hydrogen; two whole OH units are written Ca(OH)₂"
  },
  {
   "value": "Ca₂OH",
   "misconception": "you moved the 2 onto the calcium — one Ca²⁺ takes two OH⁻: Ca(OH)₂",
   "feedback": "This answer is wrong — you moved the 2 onto the calcium — one Ca²⁺ takes two OH⁻: Ca(OH)₂"
  }
 ]
}

[
 {
  "value": "H₂ClO",
  "misconception": "you added two hydrogens — one H⁺ adds exactly one H: HClO",
  "feedback": "This answer is wrong — you added two hydrogens — one H⁺ adds exactly one H: HClO"
 },
 {
  "value": "HClO⁻",
  "misconception": "you kept the 1− charge — gaining an H⁺ raises it by one, to neutral: HClO",
  "feedback": "This answer is wrong — you kept the 1− charge — gaining an H⁺ raises it by one, to neutral: HClO"
 },
 {
  "value": "ClO₂⁻",
  "misconception": "you added an oxygen instead of a hydrogen — accepting H⁺ changes the H count, not the O count",
  "feedback": "This answer is wrong — you added an oxygen instead of a hydrogen — accepting H⁺ changes the H count, not the O count"
 }
]

{
 "keyExplanation": "Accepting an H⁺ grows the formula by one H and raises the charge by one: ClO⁻ (1−) becomes the neutral particle HClO.",
 "anticipatedWrong": [
  {
   "value": "H₂ClO",
   "misconception": "you added two hydrogens — one H⁺ adds exactly one H: HClO",
   "feedback": "This answer is wrong — you added two hydrogens — one H⁺ adds exactly one H: HClO"
  },
  {
   "value": "HClO⁻",
   "misconception": "you kept the 1− charge — gaining an H⁺ raises it by one, to neutral: HClO",
   "feedback": "This answer is wrong — you kept the 1− charge — gaining an H⁺ raises it by one, to neutral: HClO"
  },
  {
   "value": "ClO₂⁻",
   "misconception": "you added an oxygen instead of a hydrogen — accepting H⁺ changes the H count, not the O count",
   "feedback": "This answer is wrong — you added an oxygen instead of a hydrogen — accepting H⁺ changes the H count, not the O count"
  }
 ]
}

[
 {
  "value": "iodous acid",
  "misconception": "you reversed the suffix — -ate points to -ic: iodATE gives iodIC acid",
  "feedback": "This answer is wrong — you reversed the suffix — -ate points to -ic: iodATE gives iodIC acid"
 },
 {
  "value": "hydroiodic acid",
  "misconception": "you added hydro- — that name belongs to the BINARY acid HI; HIO₃ is an oxyacid and takes no prefix",
  "feedback": "This answer is wrong — you added hydro- — that name belongs to the BINARY acid HI; HIO₃ is an oxyacid and takes no prefix"
 },
 {
  "value": "iodate acid",
  "misconception": "you kept the ion's name — the -ate ending converts to -ic acid in the acid's name",
  "feedback": "This answer is wrong — you kept the ion's name — the -ate ending converts to -ic acid in the acid's name"
 }
]

{
 "keyExplanation": "The ion's name ends in -ate, so the acid's name ends in -ic acid: iodate gives iodic acid — with no hydro- prefix, because that prefix belongs to binary acids.",
 "anticipatedWrong": [
  {
   "value": "iodous acid",
   "misconception": "you reversed the suffix — -ate points to -ic: iodATE gives iodIC acid",
   "feedback": "This answer is wrong — you reversed the suffix — -ate points to -ic: iodATE gives iodIC acid"
  },
  {
   "value": "hydroiodic acid",
   "misconception": "you added hydro- — that name belongs to the BINARY acid HI; HIO₃ is an oxyacid and takes no prefix",
   "feedback": "This answer is wrong — you added hydro- — that name belongs to the BINARY acid HI; HIO₃ is an oxyacid and takes no prefix"
  },
  {
   "value": "iodate acid",
   "misconception": "you kept the ion's name — the -ate ending converts to -ic acid in the acid's name",
   "feedback": "This answer is wrong — you kept the ion's name — the -ate ending converts to -ic acid in the acid's name"
  }
 ]
}

[
 {
  "value": "aluminum trihydroxide",
  "misconception": "you counted the subscript into the name — the subscript appears nowhere in a hydroxide's name: aluminum hydroxide",
  "feedback": "This answer is wrong — you counted the subscript into the name — the subscript appears nowhere in a hydroxide's name: aluminum hydroxide"
 },
 {
  "value": "aluminum(III) hydroxide",
  "misconception": "you added a Roman numeral — aluminum is a fixed-charge metal, so its name carries no numeral",
  "feedback": "This answer is wrong — you added a Roman numeral — aluminum is a fixed-charge metal, so its name carries no numeral"
 },
 {
  "value": "aluminum oxide",
  "misconception": "you dropped the hydrogens — the ion is hydroxide, OH⁻: aluminum hydroxide",
  "feedback": "This answer is wrong — you dropped the hydrogens — the ion is hydroxide, OH⁻: aluminum hydroxide"
 }
]

{
 "keyExplanation": "A metal hydroxide takes its ordinary ionic name: metal name + hydroxide. Al(OH)₃ is aluminum hydroxide — the subscript 3 appears nowhere in the name.",
 "anticipatedWrong": [
  {
   "value": "aluminum trihydroxide",
   "misconception": "you counted the subscript into the name — the subscript appears nowhere in a hydroxide's name: aluminum hydroxide",
   "feedback": "This answer is wrong — you counted the subscript into the name — the subscript appears nowhere in a hydroxide's name: aluminum hydroxide"
  },
  {
   "value": "aluminum(III) hydroxide",
   "misconception": "you added a Roman numeral — aluminum is a fixed-charge metal, so its name carries no numeral",
   "feedback": "This answer is wrong — you added a Roman numeral — aluminum is a fixed-charge metal, so its name carries no numeral"
  },
  {
   "value": "aluminum oxide",
   "misconception": "you dropped the hydrogens — the ion is hydroxide, OH⁻: aluminum hydroxide",
   "feedback": "This answer is wrong — you dropped the hydrogens — the ion is hydroxide, OH⁻: aluminum hydroxide"
  }
 ]
}

[
 {
  "value": "H₂SeO₃",
  "misconception": "you swapped in the -ite ion — -ic acid points back to selenATE, SeO₄²⁻",
  "feedback": "This answer is wrong — you swapped in the -ite ion — -ic acid points back to selenATE, SeO₄²⁻"
 },
 {
  "value": "HSeO₄",
  "misconception": "you added a single H — selenate's 2− charge takes two",
  "feedback": "This answer is wrong — you added a single H — selenate's 2− charge takes two"
 },
 {
  "value": "H₃SeO₄",
  "misconception": "you added one H too many — match the H count to the charge number, 2",
  "feedback": "This answer is wrong — you added one H too many — match the H count to the charge number, 2"
 }
]

{
 "keyExplanation": "-ic points back to the -ate ion: selenate, SeO₄²⁻. A 2− charge takes two H, so selenic acid is H₂SeO₄.",
 "anticipatedWrong": [
  {
   "value": "H₂SeO₃",
   "misconception": "you swapped in the -ite ion — -ic acid points back to selenATE, SeO₄²⁻",
   "feedback": "This answer is wrong — you swapped in the -ite ion — -ic acid points back to selenATE, SeO₄²⁻"
  },
  {
   "value": "HSeO₄",
   "misconception": "you added a single H — selenate's 2− charge takes two",
   "feedback": "This answer is wrong — you added a single H — selenate's 2− charge takes two"
  },
  {
   "value": "H₃SeO₄",
   "misconception": "you added one H too many — match the H count to the charge number, 2",
   "feedback": "This answer is wrong — you added one H too many — match the H count to the charge number, 2"
  }
 ]
}

[
 {
  "value": "NaOH",
  "misconception": "you matched the wrong use — sodium hydroxide is the drain-cleaner base; liquid soaps use potassium hydroxide, KOH",
  "feedback": "This answer is wrong — you matched the wrong use — sodium hydroxide is the drain-cleaner base; liquid soaps use potassium hydroxide, KOH"
 },
 {
  "value": "NH₃",
  "misconception": "you matched the glass-cleaner base — liquid soaps use potassium hydroxide, KOH",
  "feedback": "This answer is wrong — you matched the glass-cleaner base — liquid soaps use potassium hydroxide, KOH"
 },
 {
  "value": "Ca(OH)₂",
  "misconception": "you matched the slaked-lime base — liquid soaps use potassium hydroxide, KOH",
  "feedback": "This answer is wrong — you matched the slaked-lime base — liquid soaps use potassium hydroxide, KOH"
 }
]

{
 "keyExplanation": "Liquid soaps are made with potassium hydroxide, KOH. Sodium hydroxide clears drains, calcium hydroxide treats acidic soil as slaked lime, and ammonia cleans glass.",
 "anticipatedWrong": [
  {
   "value": "NaOH",
   "misconception": "you matched the wrong use — sodium hydroxide is the drain-cleaner base; liquid soaps use potassium hydroxide, KOH",
   "feedback": "This answer is wrong — you matched the wrong use — sodium hydroxide is the drain-cleaner base; liquid soaps use potassium hydroxide, KOH"
  },
  {
   "value": "NH₃",
   "misconception": "you matched the glass-cleaner base — liquid soaps use potassium hydroxide, KOH",
   "feedback": "This answer is wrong — you matched the glass-cleaner base — liquid soaps use potassium hydroxide, KOH"
  },
  {
   "value": "Ca(OH)₂",
   "misconception": "you matched the slaked-lime base — liquid soaps use potassium hydroxide, KOH",
   "feedback": "This answer is wrong — you matched the slaked-lime base — liquid soaps use potassium hydroxide, KOH"
  }
 ]
}

[
 {
  "value": "H₂SeO₃",
  "misconception": "you added two hydrogens — accepting ONE H⁺ adds exactly one H: HSeO₃⁻",
  "feedback": "This answer is wrong — you added two hydrogens — accepting ONE H⁺ adds exactly one H: HSeO₃⁻"
 },
 {
  "value": "HSeO₃²⁻",
  "misconception": "you added the H but kept the charge — gaining an H⁺ raises the charge by one, from 2− to 1−",
  "feedback": "This answer is wrong — you added the H but kept the charge — gaining an H⁺ raises the charge by one, from 2− to 1−"
 },
 {
  "value": "SeO₃⁻",
  "misconception": "you raised the charge without adding the H — the formula grows by one H: HSeO₃⁻",
  "feedback": "This answer is wrong — you raised the charge without adding the H — the formula grows by one H: HSeO₃⁻"
 }
]

{
 "keyExplanation": "Accepting an H⁺ grows the formula by one H and raises the charge by one: SeO₃²⁻ (2−) becomes HSeO₃⁻ (1−).",
 "anticipatedWrong": [
  {
   "value": "H₂SeO₃",
   "misconception": "you added two hydrogens — accepting ONE H⁺ adds exactly one H: HSeO₃⁻",
   "feedback": "This answer is wrong — you added two hydrogens — accepting ONE H⁺ adds exactly one H: HSeO₃⁻"
  },
  {
   "value": "HSeO₃²⁻",
   "misconception": "you added the H but kept the charge — gaining an H⁺ raises the charge by one, from 2− to 1−",
   "feedback": "This answer is wrong — you added the H but kept the charge — gaining an H⁺ raises the charge by one, from 2− to 1−"
  },
  {
   "value": "SeO₃⁻",
   "misconception": "you raised the charge without adding the H — the formula grows by one H: HSeO₃⁻",
   "feedback": "This answer is wrong — you raised the charge without adding the H — the formula grows by one H: HSeO₃⁻"
  }
 ]
}

[
 {
  "value": "phosphoric acid",
  "misconception": "you reversed the suffix — -ite points to -ous: phosphITE gives phosphorOUS acid; phosphoric belongs to phosphate",
  "feedback": "This answer is wrong — you reversed the suffix — -ite points to -ous: phosphITE gives phosphorOUS acid; phosphoric belongs to phosphate"
 },
 {
  "value": "hydrophosphorous acid",
  "misconception": "you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it",
  "feedback": "This answer is wrong — you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it"
 },
 {
  "value": "phosphite acid",
  "misconception": "you kept the ion's name — the -ite ending converts to -ous acid in the acid's name",
  "feedback": "This answer is wrong — you kept the ion's name — the -ite ending converts to -ous acid in the acid's name"
 }
]

{
 "keyExplanation": "The ion's name ends in -ite, so the acid's name ends in -ous acid: phosphite gives phosphorous acid — the root stretches so the name says smoothly, just as phosphate gives phosphoric.",
 "anticipatedWrong": [
  {
   "value": "phosphoric acid",
   "misconception": "you reversed the suffix — -ite points to -ous: phosphITE gives phosphorOUS acid; phosphoric belongs to phosphate",
   "feedback": "This answer is wrong — you reversed the suffix — -ite points to -ous: phosphITE gives phosphorOUS acid; phosphoric belongs to phosphate"
  },
  {
   "value": "hydrophosphorous acid",
   "misconception": "you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it",
   "feedback": "This answer is wrong — you added hydro- — that prefix belongs to binary acids, and oxyacid names never take it"
  },
  {
   "value": "phosphite acid",
   "misconception": "you kept the ion's name — the -ite ending converts to -ous acid in the acid's name",
   "feedback": "This answer is wrong — you kept the ion's name — the -ite ending converts to -ous acid in the acid's name"
  }
 ]
}

[
 {
  "value": "cesium oxide",
  "misconception": "you dropped the hydrogen — the ion is hydroxide, OH⁻: cesium hydroxide",
  "feedback": "This answer is wrong — you dropped the hydrogen — the ion is hydroxide, OH⁻: cesium hydroxide"
 },
 {
  "value": "hydrocesic acid",
  "misconception": "you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide",
  "feedback": "This answer is wrong — you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide"
 },
 {
  "value": "cesium hydroxide III",
  "misconception": "you appended a count — no numeral or count belongs in a fixed-charge hydroxide's name",
  "feedback": "This answer is wrong — you appended a count — no numeral or count belongs in a fixed-charge hydroxide's name"
 }
]

{
 "keyExplanation": "A metal hydroxide takes its ordinary ionic name: metal name + hydroxide. CsOH is cesium hydroxide.",
 "anticipatedWrong": [
  {
   "value": "cesium oxide",
   "misconception": "you dropped the hydrogen — the ion is hydroxide, OH⁻: cesium hydroxide",
   "feedback": "This answer is wrong — you dropped the hydrogen — the ion is hydroxide, OH⁻: cesium hydroxide"
  },
  {
   "value": "hydrocesic acid",
   "misconception": "you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide",
   "feedback": "This answer is wrong — you used an acid pattern — hydro-, -ic, and -ous belong to acids; a metal hydroxide takes metal name + hydroxide"
  },
  {
   "value": "cesium hydroxide III",
   "misconception": "you appended a count — no numeral or count belongs in a fixed-charge hydroxide's name",
   "feedback": "This answer is wrong — you appended a count — no numeral or count belongs in a fixed-charge hydroxide's name"
  }
 ]
}

[
 {
  "value": "HBrO₂",
  "misconception": "you reversed -ic to the wrong ion — -ic acid points back to bromATE, BrO₃⁻; BrO₂⁻ is bromite",
  "feedback": "This answer is wrong — you reversed -ic to the wrong ion — -ic acid points back to bromATE, BrO₃⁻; BrO₂⁻ is bromite"
 },
 {
  "value": "H₂BrO₃",
  "misconception": "you doubled the hydrogen — bromate's 1− charge needs only one H",
  "feedback": "This answer is wrong — you doubled the hydrogen — bromate's 1− charge needs only one H"
 },
 {
  "value": "HBr",
  "misconception": "you dropped the oxygens — bromic acid is an oxyacid; HBr is hydrobromic, the binary acid",
  "feedback": "This answer is wrong — you dropped the oxygens — bromic acid is an oxyacid; HBr is hydrobromic, the binary acid"
 }
]

{
 "keyExplanation": "-ic points back to the -ate ion: bromate, BrO₃⁻. A 1− charge takes one H, so bromic acid is HBrO₃.",
 "anticipatedWrong": [
  {
   "value": "HBrO₂",
   "misconception": "you reversed -ic to the wrong ion — -ic acid points back to bromATE, BrO₃⁻; BrO₂⁻ is bromite",
   "feedback": "This answer is wrong — you reversed -ic to the wrong ion — -ic acid points back to bromATE, BrO₃⁻; BrO₂⁻ is bromite"
  },
  {
   "value": "H₂BrO₃",
   "misconception": "you doubled the hydrogen — bromate's 1− charge needs only one H",
   "feedback": "This answer is wrong — you doubled the hydrogen — bromate's 1− charge needs only one H"
  },
  {
   "value": "HBr",
   "misconception": "you dropped the oxygens — bromic acid is an oxyacid; HBr is hydrobromic, the binary acid",
   "feedback": "This answer is wrong — you dropped the oxygens — bromic acid is an oxyacid; HBr is hydrobromic, the binary acid"
  }
 ]
}

[
 {
  "value": 4,
  "misconception": "you gave the number of pH units instead of the factor — each unit multiplies the [H⁺] by ten",
  "feedback": "This answer is wrong — you gave the number of pH units instead of the factor — each unit multiplies the [H⁺] by ten."
 },
 {
  "value": 40,
  "misconception": "you multiplied the unit count by ten instead of stacking a factor of ten per unit",
  "feedback": "This answer is wrong — you multiplied the unit count by ten instead of stacking a factor of ten per unit."
 },
 {
  "value": 1000,
  "misconception": "you stopped a factor of ten short — count all 4 units between 3 and 7",
  "feedback": "This answer is wrong — you stopped a factor of ten short — count all 4 units between 3 and 7."
 }
]

{
 "keyExplanation": "Count the units between the two pH values: 7 − 3 = 4 units. Each unit is a factor of ten: 10 × 10 × 10 × 10 = 10000. The lower pH marks the greater [H⁺], so the factor is 10000."
}

[
 {
  "value": -3,
  "misconception": "you kept the exponent's minus sign — the equation's minus flips −3 to 3",
  "feedback": "This answer is wrong — you kept the exponent's minus sign — the equation's minus flips −3 to 3."
 },
 {
  "value": 11,
  "misconception": "you subtracted the exponent from 14 — no such step exists in this calculation",
  "feedback": "This answer is wrong — you subtracted the exponent from 14 — no such step exists in this calculation."
 },
 {
  "value": 0.001,
  "misconception": "you gave the concentration back instead of the pH",
  "feedback": "This answer is wrong — you gave the concentration back instead of the pH."
 }
]

{
 "keyExplanation": "Write down the values in the question: [H⁺] = 1 × 10⁻³ M Write down the equation: pH = −log[H⁺] Substitute in the values, and calculate: pH = −log(1 × 10⁻³) = −(−3) pH = 3"
}

[
 {
  "value": 12,
  "misconception": "you miscounted the decimal places — thirteen places means 1 × 10⁻¹³ M",
  "feedback": "This answer is wrong — you miscounted the decimal places — thirteen places means 1 × 10⁻¹³ M."
 },
 {
  "value": -13,
  "misconception": "you kept the exponent's minus sign — the equation's minus flips −13 to 13",
  "feedback": "This answer is wrong — you kept the exponent's minus sign — the equation's minus flips −13 to 13."
 },
 {
  "value": 1,
  "misconception": "you subtracted the exponent from 14 — no such step exists in this calculation",
  "feedback": "This answer is wrong — you subtracted the exponent from 14 — no such step exists in this calculation."
 }
]

{
 "keyExplanation": "Write down the values in the question: [H⁺] = 0.0000000000001 M Rewrite as a power of ten: [H⁺] = 1 × 10⁻¹³ M Write down the equation: pH = −log[H⁺] Substitute in the values, and calculate: pH = −log(1 × 10⁻¹³) = −(−13) pH = 13"
}

[
 {
  "value": 100000000000.0,
  "misconception": "you dropped the minus sign in the exponent — the pH enters as MINUS the pH",
  "feedback": "This answer is wrong — you dropped the minus sign in the exponent — the pH enters as MINUS the pH."
 },
 {
  "value": 0.001,
  "misconception": "you subtracted the pH from 14 first — no such step exists in this relationship",
  "feedback": "This answer is wrong — you subtracted the pH from 14 first — no such step exists in this relationship."
 },
 {
  "value": 11.0,
  "misconception": "you gave the pH itself back as a concentration — the pH must move into the exponent",
  "feedback": "This answer is wrong — you gave the pH itself back as a concentration — the pH must move into the exponent."
 }
]

{
 "keyExplanation": "Write down the values in the question: pH = 11 Write down the equation: pH = −log[H⁺] Make [H⁺] the subject: [H⁺] = 1 × 10⁻ᵖᴴ Substitute in the values, and calculate: [H⁺] = 1 × 10⁻¹¹ [H⁺] = 1 × 10⁻¹¹ M"
}

[
 {
  "value": 6,
  "misconception": "you gave the number of pH units instead of the factor — each unit multiplies the [H⁺] by ten",
  "feedback": "This answer is wrong — you gave the number of pH units instead of the factor — each unit multiplies the [H⁺] by ten."
 },
 {
  "value": 60,
  "misconception": "you multiplied the unit count by ten instead of stacking a factor of ten per unit",
  "feedback": "This answer is wrong — you multiplied the unit count by ten instead of stacking a factor of ten per unit."
 },
 {
  "value": 100000,
  "misconception": "you stopped a factor of ten short — count all 6 units between 2 and 8",
  "feedback": "This answer is wrong — you stopped a factor of ten short — count all 6 units between 2 and 8."
 }
]

{
 "keyExplanation": "Count the units between the two pH values: 8 − 2 = 6 units. Each unit is a factor of ten: 10 × 10 × 10 × 10 × 10 × 10 = 1000000. The lower pH marks the greater [H⁺], so the factor is 1000000."
}

[
 {
  "value": -6,
  "misconception": "you kept the exponent's minus sign — the equation's minus flips −6 to 6",
  "feedback": "This answer is wrong — you kept the exponent's minus sign — the equation's minus flips −6 to 6."
 },
 {
  "value": 8,
  "misconception": "you subtracted the exponent from 14 — no such step exists in this calculation",
  "feedback": "This answer is wrong — you subtracted the exponent from 14 — no such step exists in this calculation."
 },
 {
  "value": 1e-06,
  "misconception": "you gave the concentration back instead of the pH",
  "feedback": "This answer is wrong — you gave the concentration back instead of the pH."
 }
]

{
 "keyExplanation": "Write down the values in the question: [H⁺] = 1 × 10⁻⁶ M Write down the equation: pH = −log[H⁺] Substitute in the values, and calculate: pH = −log(1 × 10⁻⁶) = −(−6) pH = 6"
}

[
 {
  "value": 10,
  "misconception": "you miscounted the decimal places — eleven places means 1 × 10⁻¹¹ M",
  "feedback": "This answer is wrong — you miscounted the decimal places — eleven places means 1 × 10⁻¹¹ M."
 },
 {
  "value": -11,
  "misconception": "you kept the exponent's minus sign — the equation's minus flips −11 to 11",
  "feedback": "This answer is wrong — you kept the exponent's minus sign — the equation's minus flips −11 to 11."
 },
 {
  "value": 3,
  "misconception": "you subtracted the exponent from 14 — no such step exists in this calculation",
  "feedback": "This answer is wrong — you subtracted the exponent from 14 — no such step exists in this calculation."
 }
]

{
 "keyExplanation": "Write down the values in the question: [H⁺] = 0.00000000001 M Rewrite as a power of ten: [H⁺] = 1 × 10⁻¹¹ M Write down the equation: pH = −log[H⁺] Substitute in the values, and calculate: pH = −log(1 × 10⁻¹¹) = −(−11) pH = 11"
}

[
 {
  "value": 100.0,
  "misconception": "you dropped the minus sign in the exponent — the pH enters as MINUS the pH",
  "feedback": "This answer is wrong — you dropped the minus sign in the exponent — the pH enters as MINUS the pH."
 },
 {
  "value": 1e-12,
  "misconception": "you subtracted the pH from 14 first — no such step exists in this relationship",
  "feedback": "This answer is wrong — you subtracted the pH from 14 first — no such step exists in this relationship."
 },
 {
  "value": 2.0,
  "misconception": "you gave the pH itself back as a concentration — the pH must move into the exponent",
  "feedback": "This answer is wrong — you gave the pH itself back as a concentration — the pH must move into the exponent."
 }
]

{
 "keyExplanation": "Write down the values in the question: pH = 2 Write down the equation: pH = −log[H⁺] Make [H⁺] the subject: [H⁺] = 1 × 10⁻ᵖᴴ Substitute in the values, and calculate: [H⁺] = 1 × 10⁻² [H⁺] = 1 × 10⁻² M"
}

[
 {
  "value": 7,
  "misconception": "you gave the number of pH units instead of the factor — each unit multiplies the [H⁺] by ten",
  "feedback": "This answer is wrong — you gave the number of pH units instead of the factor — each unit multiplies the [H⁺] by ten."
 },
 {
  "value": 70,
  "misconception": "you multiplied the unit count by ten instead of stacking a factor of ten per unit",
  "feedback": "This answer is wrong — you multiplied the unit count by ten instead of stacking a factor of ten per unit."
 },
 {
  "value": 1000000,
  "misconception": "you stopped a factor of ten short — count all 7 units between 3 and 10",
  "feedback": "This answer is wrong — you stopped a factor of ten short — count all 7 units between 3 and 10."
 }
]

{
 "keyExplanation": "Count the units between the two pH values: 10 − 3 = 7 units. Each unit is a factor of ten: 10 × 10 × 10 × 10 × 10 × 10 × 10 = 10000000. The lower pH marks the greater [H⁺], so the factor is 10000000."
}

[
 {
  "value": -4,
  "misconception": "you kept the exponent's minus sign — the equation's minus flips −4 to 4",
  "feedback": "This answer is wrong — you kept the exponent's minus sign — the equation's minus flips −4 to 4."
 },
 {
  "value": 10,
  "misconception": "you subtracted the exponent from 14 — no such step exists in this calculation",
  "feedback": "This answer is wrong — you subtracted the exponent from 14 — no such step exists in this calculation."
 },
 {
  "value": 0.0001,
  "misconception": "you gave the concentration back instead of the pH",
  "feedback": "This answer is wrong — you gave the concentration back instead of the pH."
 }
]

{
 "keyExplanation": "Write down the values in the question: [H⁺] = 1 × 10⁻⁴ M Write down the equation: pH = −log[H⁺] Substitute in the values, and calculate: pH = −log(1 × 10⁻⁴) = −(−4) pH = 4"
}

[
 {
  "value": 7,
  "misconception": "you miscounted the decimal places — eight places means 1 × 10⁻⁸ M",
  "feedback": "This answer is wrong — you miscounted the decimal places — eight places means 1 × 10⁻⁸ M."
 },
 {
  "value": -8,
  "misconception": "you kept the exponent's minus sign — the equation's minus flips −8 to 8",
  "feedback": "This answer is wrong — you kept the exponent's minus sign — the equation's minus flips −8 to 8."
 },
 {
  "value": 6,
  "misconception": "you subtracted the exponent from 14 — no such step exists in this calculation",
  "feedback": "This answer is wrong — you subtracted the exponent from 14 — no such step exists in this calculation."
 }
]

{
 "keyExplanation": "Write down the values in the question: [H⁺] = 0.00000001 M Rewrite as a power of ten: [H⁺] = 1 × 10⁻⁸ M Write down the equation: pH = −log[H⁺] Substitute in the values, and calculate: pH = −log(1 × 10⁻⁸) = −(−8) pH = 8"
}

[
 {
  "value": 100000,
  "misconception": "you dropped the minus sign in the exponent — the pH enters as MINUS the pH",
  "feedback": "This answer is wrong — you dropped the minus sign in the exponent — the pH enters as MINUS the pH."
 },
 {
  "value": 1e-09,
  "misconception": "you subtracted the pH from 14 first — no such step exists in this relationship",
  "feedback": "This answer is wrong — you subtracted the pH from 14 first — no such step exists in this relationship."
 },
 {
  "value": 5,
  "misconception": "you gave the pH itself back as a concentration — the pH must move into the exponent",
  "feedback": "This answer is wrong — you gave the pH itself back as a concentration — the pH must move into the exponent."
 }
]

{
 "keyExplanation": "Write down the values in the question: pH = 5 Write down the equation: pH = −log[H⁺] Make [H⁺] the subject: [H⁺] = 1 × 10⁻ᵖᴴ M Substitute in the values, and calculate: [H⁺] = 1 × 10⁻⁵ M = 0.00001 M"
}

[
 {
  "value": 8,
  "misconception": "you gave the number of pH units instead of the factor — each unit multiplies the [H⁺] by ten",
  "feedback": "This answer is wrong — you gave the number of pH units instead of the factor — each unit multiplies the [H⁺] by ten."
 },
 {
  "value": 80,
  "misconception": "you multiplied the unit count by ten instead of stacking a factor of ten per unit",
  "feedback": "This answer is wrong — you multiplied the unit count by ten instead of stacking a factor of ten per unit."
 },
 {
  "value": 10000000,
  "misconception": "you stopped a factor of ten short — count all 8 units between 2 and 10",
  "feedback": "This answer is wrong — you stopped a factor of ten short — count all 8 units between 2 and 10."
 }
]

{
 "keyExplanation": "Count the units between the two pH values: 10 − 2 = 8 units. Each unit is a factor of ten: 10 × 10 × 10 × 10 × 10 × 10 × 10 × 10 = 100000000. The lower pH marks the greater [H⁺], so the factor is 100000000."
}

[
 {
  "value": -12,
  "misconception": "you kept the exponent's minus sign — the equation's minus flips −12 to 12",
  "feedback": "This answer is wrong — you kept the exponent's minus sign — the equation's minus flips −12 to 12."
 },
 {
  "value": 2,
  "misconception": "you subtracted the exponent from 14 — no such step exists in this calculation",
  "feedback": "This answer is wrong — you subtracted the exponent from 14 — no such step exists in this calculation."
 },
 {
  "value": 1e-12,
  "misconception": "you gave the concentration back instead of the pH",
  "feedback": "This answer is wrong — you gave the concentration back instead of the pH."
 }
]

{
 "keyExplanation": "Write down the values in the question: [H⁺] = 1 × 10⁻¹² M Write down the equation: pH = −log[H⁺] Substitute in the values, and calculate: pH = −log(1 × 10⁻¹²) = −(−12) pH = 12"
}

[
 {
  "value": 6,
  "misconception": "you miscounted the decimal places — seven places means 1 × 10⁻⁷ M",
  "feedback": "This answer is wrong — you miscounted the decimal places — seven places means 1 × 10⁻⁷ M."
 },
 {
  "value": -7,
  "misconception": "you kept the exponent's minus sign — the equation's minus flips −7 to 7",
  "feedback": "This answer is wrong — you kept the exponent's minus sign — the equation's minus flips −7 to 7."
 },
 {
  "value": 8,
  "misconception": "you counted one decimal place too many — the concentration has seven places, so the exponent is −7",
  "feedback": "This answer is wrong — you counted one decimal place too many — the concentration has seven places, so the exponent is −7."
 }
]

{
 "keyExplanation": "Write down the values in the question: [H⁺] = 0.0000001 M Rewrite as a power of ten: [H⁺] = 1 × 10⁻⁷ M Write down the equation: pH = −log[H⁺] Substitute in the values, and calculate: pH = −log(1 × 10⁻⁷) = −(−7) pH = 7"
}

[
 {
  "value": 1000000000.0,
  "misconception": "you dropped the minus sign in the exponent — the pH enters as MINUS the pH",
  "feedback": "This answer is wrong — you dropped the minus sign in the exponent — the pH enters as MINUS the pH."
 },
 {
  "value": 1e-05,
  "misconception": "you subtracted the pH from 14 first — no such step exists in this relationship",
  "feedback": "This answer is wrong — you subtracted the pH from 14 first — no such step exists in this relationship."
 },
 {
  "value": 9.0,
  "misconception": "you gave the pH itself back as a concentration — the pH must move into the exponent",
  "feedback": "This answer is wrong — you gave the pH itself back as a concentration — the pH must move into the exponent."
 }
]

{
 "keyExplanation": "Write down the values in the question: pH = 9 Write down the equation: pH = −log[H⁺] Make [H⁺] the subject: [H⁺] = 1 × 10⁻ᵖᴴ Substitute in the values, and calculate: [H⁺] = 1 × 10⁻⁹ [H⁺] = 1 × 10⁻⁹ M"
}

[
 {
  "value": 9,
  "misconception": "you gave the number of pH units instead of the factor — each unit multiplies the [H⁺] by ten",
  "feedback": "This answer is wrong — you gave the number of pH units instead of the factor — each unit multiplies the [H⁺] by ten."
 },
 {
  "value": 90,
  "misconception": "you multiplied the unit count by ten instead of stacking a factor of ten per unit",
  "feedback": "This answer is wrong — you multiplied the unit count by ten instead of stacking a factor of ten per unit."
 },
 {
  "value": 100000000,
  "misconception": "you stopped a factor of ten short — count all 9 units between 1 and 10",
  "feedback": "This answer is wrong — you stopped a factor of ten short — count all 9 units between 1 and 10."
 }
]

{
 "keyExplanation": "Count the units between the two pH values: 10 − 1 = 9 units. Each unit is a factor of ten: 10 × 10 × 10 × 10 × 10 × 10 × 10 × 10 × 10 = 1000000000. The lower pH marks the greater [H⁺], so the factor is 1000000000."
}

[
 {
  "value": -9,
  "misconception": "you kept the exponent's minus sign — the equation's minus flips −9 to 9",
  "feedback": "This answer is wrong — you kept the exponent's minus sign — the equation's minus flips −9 to 9."
 },
 {
  "value": 5,
  "misconception": "you subtracted the exponent from 14 — no such step exists in this calculation",
  "feedback": "This answer is wrong — you subtracted the exponent from 14 — no such step exists in this calculation."
 },
 {
  "value": 1e-09,
  "misconception": "you gave the concentration back instead of the pH",
  "feedback": "This answer is wrong — you gave the concentration back instead of the pH."
 }
]

{
 "keyExplanation": "Write down the values in the question: [H⁺] = 1 × 10⁻⁹ M Write down the equation: pH = −log[H⁺] Substitute in the values, and calculate: pH = −log(1 × 10⁻⁹) = −(−9) pH = 9"
}

[
 {
  "value": 2,
  "misconception": "you miscounted the decimal places — three places means 1 × 10⁻³ M",
  "feedback": "This answer is wrong — you miscounted the decimal places — three places means 1 × 10⁻³ M."
 },
 {
  "value": -3,
  "misconception": "you kept the exponent's minus sign — the equation's minus flips −3 to 3",
  "feedback": "This answer is wrong — you kept the exponent's minus sign — the equation's minus flips −3 to 3."
 },
 {
  "value": 11,
  "misconception": "you subtracted the exponent from 14 — no such step exists in this calculation",
  "feedback": "This answer is wrong — you subtracted the exponent from 14 — no such step exists in this calculation."
 }
]

{
 "keyExplanation": "Write down the values in the question: [H⁺] = 0.001 M Rewrite as a power of ten: [H⁺] = 1 × 10⁻³ M Write down the equation: pH = −log[H⁺] Substitute in the values, and calculate: pH = −log(1 × 10⁻³) = −(−3) pH = 3"
}

[
 {
  "value": 1000000.0,
  "misconception": "you dropped the minus sign in the exponent — the pH enters as MINUS the pH",
  "feedback": "This answer is wrong — you dropped the minus sign in the exponent — the pH enters as MINUS the pH."
 },
 {
  "value": 1e-08,
  "misconception": "you subtracted the pH from 14 first — no such step exists in this relationship",
  "feedback": "This answer is wrong — you subtracted the pH from 14 first — no such step exists in this relationship."
 },
 {
  "value": 6.0,
  "misconception": "you gave the pH itself back as a concentration — the pH must move into the exponent",
  "feedback": "This answer is wrong — you gave the pH itself back as a concentration — the pH must move into the exponent."
 }
]

{
 "keyExplanation": "Write down the values in the question: pH = 6 Write down the equation: pH = −log[H⁺] Make [H⁺] the subject: [H⁺] = 1 × 10⁻ᵖᴴ Substitute in the values, and calculate: [H⁺] = 1 × 10⁻⁶ [H⁺] = 1 × 10⁻⁶ M"
}

[
 {
  "value": "CaH₂",
  "misconception": "you paired the metal with the acid's hydrogen — the salt takes the acid's NEGATIVE ion, I⁻",
  "feedback": null
 },
 {
  "value": "CaI",
  "misconception": "you ignored the charges — one 1− iodide cannot balance a 2+ calcium; calcium's 2 must cross to the iodide",
  "feedback": null
 },
 {
  "value": "Ca₂I",
  "misconception": "you criss-crossed in reverse — calcium's 2 becomes the IODIDE's subscript, not calcium's own",
  "feedback": null
 }
]

{
 "keyExplanation": "The acid's negative ion: HI gives I⁻. The base's metal ion: Ca(OH)₂ gives Ca²⁺. Criss-cross the charges: calcium's 2 crosses to the iodide, giving CaI₂. Water forms alongside it."
}

[
 {
  "value": "HNO₃ + NaOH → NaNO₃ + H₂",
  "misconception": "you released hydrogen gas — with a base, the acid's hydrogen ends up in water, not H₂",
  "feedback": null
 },
 {
  "value": "HNO₃ + NaOH → NaNO₃",
  "misconception": "you dropped the water — the acid's H⁺ and the base's OH⁻ pair up and must appear as the product H₂O",
  "feedback": null
 },
 {
  "value": "2HNO₃ + 2NaOH → 2NaNO₃ + 2H₂O",
  "misconception": "your equation is balanced, but not written in the smallest whole-number coefficients — every coefficient here can be divided by two",
  "feedback": null
 }
]

{
 "keyExplanation": "Products: the salt NaNO₃ and water. Count the pairs: one H⁺ from HNO₃, one OH⁻ from NaOH — the counts match, so no coefficients are needed. HNO₃ + NaOH → NaNO₃ + H₂O. Check: 2 H, 1 N, 4 O, 1 Na on each side."
}

[
 {
  "value": 0.07,
  "misconception": "you swapped the two volumes — the unknown's OWN volume is the divisor",
  "feedback": null
 },
 {
  "value": 0.14,
  "misconception": "you assumed the two molarities match — they match only when the two volumes match",
  "feedback": null
 },
 {
  "value": 11.8,
  "misconception": "you multiplied the known side but never divided by the acid's volume",
  "feedback": null
 }
]

{
 "keyExplanation": "Write down the values in the question:\nV(acid) = 42.0 mL\nM(base) = 0.140 M\nV(base) = 84.0 mL\nWrite down the equation:\nM(acid) × V(acid) = M(base) × V(base)\nMake M(acid) the subject:\nM(acid) = M(base) × V(base) ÷ V(acid)\nSubstitute in the values, and calculate:\nM(acid) = 0.140 × 84.0 ÷ 42.0\nM(acid) = 0.280 M\nSanity check: the acid needed half the base's volume, so it comes out twice as concentrated — 0.280 M against 0.140 M passes."
}

[
 {
  "value": 1.17,
  "misconception": "you swapped the two volumes — the unknown's OWN volume is the divisor",
  "feedback": null
 },
 {
  "value": 0.39,
  "misconception": "you assumed the two molarities match — they match only when the two volumes match",
  "feedback": null
 },
 {
  "value": 10.5,
  "misconception": "you multiplied the known side but never divided by the base's volume",
  "feedback": null
 }
]

{
 "keyExplanation": "Write down the values in the question:\nV(base) = 81.0 mL\nM(acid) = 0.390 M\nV(acid) = 27.0 mL\nWrite down the equation:\nM(acid) × V(acid) = M(base) × V(base)\nMake M(base) the subject:\nM(base) = M(acid) × V(acid) ÷ V(base)\nSubstitute in the values, and calculate:\nM(base) = 0.390 × 27.0 ÷ 81.0\nM(base) = 0.130 M\nSanity check: the base needed three times the acid's volume, so it comes out a third as concentrated — 0.130 M against 0.390 M passes."
}

[
 {
  "value": "CaNO₃",
  "misconception": "you ignored the charges — one 1− nitrate cannot balance a 2+ calcium; calcium's 2 must cross to the nitrate",
  "feedback": null
 },
 {
  "value": "Ca₂NO₃",
  "misconception": "you criss-crossed in reverse — calcium's 2 belongs on the nitrate group, outside its parentheses, not on calcium itself",
  "feedback": null
 },
 {
  "value": "CaN₂O₆",
  "misconception": "you multiplied out the atoms — the nitrate ion stays whole, in parentheses, with its subscript outside",
  "feedback": null
 }
]

{
 "keyExplanation": "The acid's negative ion: HNO₃ gives NO₃⁻. The base's metal ion: Ca(OH)₂ gives Ca²⁺. Criss-cross the charges: calcium's 2 crosses to the nitrate, which keeps its parentheses, giving Ca(NO₃)₂. Water forms alongside it."
}

[
 {
  "value": "HNO₃ + NaOH → NaNO₃ + H₂",
  "misconception": "you released hydrogen gas — with a base, the acid's hydrogen ends up in water, not H₂",
  "feedback": null
 },
 {
  "value": "HNO₃ + NaOH → NaNO₃",
  "misconception": "you dropped the water — the acid's H⁺ and the base's OH⁻ pair up and must appear as the product H₂O",
  "feedback": null
 },
 {
  "value": "2HNO₃ + 2NaOH → 2NaNO₃ + 2H₂O",
  "misconception": "your equation is balanced, but not written in the smallest whole-number coefficients — every coefficient here can be divided by two",
  "feedback": null
 }
]

{
 "keyExplanation": "Products: the salt NaNO₃ and water. Count the pairs: one H⁺ from HNO₃, one OH⁻ from NaOH — the counts match, so no coefficients are needed. HNO₃ + NaOH → NaNO₃ + H₂O. Check: 2 H, 1 N, 4 O, 1 Na on each side."
}

[
 {
  "value": 1.98,
  "misconception": "you swapped the two volumes — the unknown's OWN volume is the divisor",
  "feedback": null
 },
 {
  "value": 0.66,
  "misconception": "you assumed the two molarities match — they match only when the two volumes match",
  "feedback": null
 },
 {
  "value": 17.2,
  "misconception": "you multiplied the known side but never divided by the acid's volume",
  "feedback": null
 }
]

{
 "keyExplanation": "Write down the values in the question:\nV(acid) = 78.0 mL\nM(base) = 0.660 M\nV(base) = 26.0 mL\nWrite down the equation:\nM(acid) × V(acid) = M(base) × V(base)\nMake M(acid) the subject:\nM(acid) = M(base) × V(base) ÷ V(acid)\nSubstitute in the values, and calculate:\nM(acid) = 0.660 × 26.0 ÷ 78.0\nM(acid) = 0.220 M\nSanity check: the acid needed three times the base's volume, so it comes out a third as concentrated — 0.220 M against 0.660 M passes."
}

[
 {
  "value": 0.115,
  "misconception": "you swapped the two volumes — the unknown's OWN volume is the divisor",
  "feedback": null
 },
 {
  "value": 0.23,
  "misconception": "you assumed the two molarities match — they match only when the two volumes match",
  "feedback": null
 },
 {
  "value": 7.82,
  "misconception": "you multiplied the known side but never divided by the base's volume",
  "feedback": null
 }
]

{
 "keyExplanation": "Write down the values in the question:\nV(base) = 17.0 mL\nM(acid) = 0.230 M\nV(acid) = 34.0 mL\nWrite down the equation:\nM(acid) × V(acid) = M(base) × V(base)\nMake M(base) the subject:\nM(base) = M(acid) × V(acid) ÷ V(base)\nSubstitute in the values, and calculate:\nM(base) = 0.230 × 34.0 ÷ 17.0\nM(base) = 0.460 M\nSanity check: the base needed half the acid's volume, so it comes out twice as concentrated — 0.460 M against 0.230 M passes."
}

[
 {
  "value": "CaH₂",
  "misconception": "you paired the metal with the acid's hydrogen — the salt takes the acid's NEGATIVE ion, I⁻",
  "feedback": null
 },
 {
  "value": "CaI",
  "misconception": "you ignored the charges — one 1− iodide cannot balance a 2+ calcium; calcium's 2 must cross to the iodide",
  "feedback": null
 },
 {
  "value": "Ca₂I",
  "misconception": "you criss-crossed in reverse — calcium's 2 becomes the IODIDE's subscript, not calcium's own",
  "feedback": null
 }
]

{
 "keyExplanation": "The acid's negative ion: HI gives I⁻. The base's metal ion: Ca(OH)₂ gives Ca²⁺. Criss-cross the charges: calcium's 2 crosses to the iodide, giving CaI₂. Water forms alongside it."
}

[
 {
  "value": "HNO₃ + NaOH → NaNO₃ + H₂",
  "misconception": "you released hydrogen gas — with a base, the acid's hydrogen ends up in water, not H₂",
  "feedback": null
 },
 {
  "value": "HNO₃ + NaOH → NaNO₃",
  "misconception": "you dropped the water — the acid's H⁺ and the base's OH⁻ pair up and must appear as the product H₂O",
  "feedback": null
 },
 {
  "value": "2HNO₃ + 2NaOH → 2NaNO₃ + 2H₂O",
  "misconception": "your equation is balanced, but not written in the smallest whole-number coefficients — every coefficient here can be divided by two",
  "feedback": null
 }
]

{
 "keyExplanation": "Products: the salt NaNO₃ and water. Count the pairs: one H⁺ from HNO₃, one OH⁻ from NaOH — the counts match, so no coefficients are needed. HNO₃ + NaOH → NaNO₃ + H₂O. Check: 2 H, 1 N, 4 O, 1 Na on each side."
}

[
 {
  "value": 0.06,
  "misconception": "you swapped the two volumes — the unknown's OWN volume is the divisor",
  "feedback": null
 },
 {
  "value": 0.18,
  "misconception": "you assumed the two molarities match — they match only when the two volumes match",
  "feedback": null
 },
 {
  "value": 10.3,
  "misconception": "you multiplied the known side but never divided by the acid's volume",
  "feedback": null
 }
]

{
 "keyExplanation": "Write down the values in the question:\nV(acid) = 19.0 mL\nM(base) = 0.180 M\nV(base) = 57.0 mL\nWrite down the equation:\nM(acid) × V(acid) = M(base) × V(base)\nMake M(acid) the subject:\nM(acid) = M(base) × V(base) ÷ V(acid)\nSubstitute in the values, and calculate:\nM(acid) = 0.180 × 57.0 ÷ 19.0\nM(acid) = 0.540 M\nSanity check: the acid needed a third of the base's volume, so it comes out three times as concentrated — 0.540 M against 0.180 M passes."
}

[
 {
  "value": 0.105,
  "misconception": "you swapped the two volumes — the unknown's OWN volume is the divisor",
  "feedback": null
 },
 {
  "value": 0.21,
  "misconception": "you assumed the two molarities match — they match only when the two volumes match",
  "feedback": null
 },
 {
  "value": 13.4,
  "misconception": "you multiplied the known side but never divided by the base's volume",
  "feedback": null
 }
]

{
 "keyExplanation": "Write down the values in the question:\nV(base) = 32.0 mL\nM(acid) = 0.210 M\nV(acid) = 64.0 mL\nWrite down the equation:\nM(acid) × V(acid) = M(base) × V(base)\nMake M(base) the subject:\nM(base) = M(acid) × V(acid) ÷ V(base)\nSubstitute in the values, and calculate:\nM(base) = 0.210 × 64.0 ÷ 32.0\nM(base) = 0.420 M\nSanity check: the base needed half the acid's volume, so it comes out twice as concentrated — 0.420 M against 0.210 M passes."
}

[
 {
  "value": "CaNO₃",
  "misconception": "you ignored the charges — one 1− nitrate cannot balance a 2+ calcium; calcium's 2 must cross to the nitrate",
  "feedback": null
 },
 {
  "value": "Ca₂NO₃",
  "misconception": "you criss-crossed in reverse — calcium's 2 belongs on the nitrate group, outside its parentheses, not on calcium itself",
  "feedback": null
 },
 {
  "value": "CaN₂O₆",
  "misconception": "you multiplied out the atoms — the nitrate ion stays whole, in parentheses, with its subscript outside",
  "feedback": null
 }
]

{
 "keyExplanation": "The acid's negative ion: HNO₃ gives NO₃⁻. The base's metal ion: Ca(OH)₂ gives Ca²⁺. Criss-cross the charges: calcium's 2 crosses to the nitrate, which keeps its parentheses, giving Ca(NO₃)₂. Water forms alongside it."
}

[
 {
  "value": "HNO₃ + NaOH → NaNO₃ + H₂",
  "misconception": "you released hydrogen gas — with a base, the acid's hydrogen ends up in water, not H₂",
  "feedback": null
 },
 {
  "value": "HNO₃ + NaOH → NaNO₃",
  "misconception": "you dropped the water — the acid's H⁺ and the base's OH⁻ pair up and must appear as the product H₂O",
  "feedback": null
 },
 {
  "value": "2HNO₃ + 2NaOH → 2NaNO₃ + 2H₂O",
  "misconception": "your equation is balanced, but not written in the smallest whole-number coefficients — every coefficient here can be divided by two",
  "feedback": null
 }
]

{
 "keyExplanation": "Products: the salt NaNO₃ and water. Count the pairs: one H⁺ from HNO₃, one OH⁻ from NaOH — the counts match, so no coefficients are needed. HNO₃ + NaOH → NaNO₃ + H₂O. Check: 2 H, 1 N, 4 O, 1 Na on each side."
}

[
 {
  "value": 0.563,
  "misconception": "you swapped the two volumes — the unknown's OWN volume is the divisor",
  "feedback": null
 },
 {
  "value": 0.45,
  "misconception": "you assumed the two molarities match — they match only when the two volumes match",
  "feedback": null
 },
 {
  "value": 19.8,
  "misconception": "you multiplied the known side but never divided by the acid's volume",
  "feedback": null
 }
]

{
 "keyExplanation": "Write down the values in the question:\nV(acid) = 55.0 mL\nM(base) = 0.450 M\nV(base) = 44.0 mL\nWrite down the equation:\nM(acid) × V(acid) = M(base) × V(base)\nMake M(acid) the subject:\nM(acid) = M(base) × V(base) ÷ V(acid)\nSubstitute in the values, and calculate:\nM(acid) = 0.450 × 44.0 ÷ 55.0\nM(acid) = 0.360 M\nSanity check: the acid needed more volume than the base, so it comes out less concentrated — 0.360 M against 0.450 M passes."
}

[
 {
  "value": 3.04,
  "misconception": "you swapped the two volumes — the unknown's OWN volume is the divisor",
  "feedback": null
 },
 {
  "value": 0.76,
  "misconception": "you assumed the two molarities match — they match only when the two volumes match",
  "feedback": null
 },
 {
  "value": 16.7,
  "misconception": "you multiplied the known side but never divided by the base's volume",
  "feedback": null
 }
]

{
 "keyExplanation": "Write down the values in the question:\nV(base) = 88.0 mL\nM(acid) = 0.760 M\nV(acid) = 22.0 mL\nWrite down the equation:\nM(acid) × V(acid) = M(base) × V(base)\nMake M(base) the subject:\nM(base) = M(acid) × V(acid) ÷ V(base)\nSubstitute in the values, and calculate:\nM(base) = 0.760 × 22.0 ÷ 88.0\nM(base) = 0.190 M\nSanity check: the base needed four times the acid's volume, so it comes out a quarter as concentrated — 0.190 M against 0.760 M passes."
}

[
 {
  "value": "CaH₂",
  "misconception": "you paired the metal with the acid's hydrogen — the salt takes the acid's NEGATIVE ion, I⁻",
  "feedback": null
 },
 {
  "value": "CaI",
  "misconception": "you ignored the charges — one 1− iodide cannot balance a 2+ calcium; calcium's 2 must cross to the iodide",
  "feedback": null
 },
 {
  "value": "Ca₂I",
  "misconception": "you criss-crossed in reverse — calcium's 2 becomes the IODIDE's subscript, not calcium's own",
  "feedback": null
 }
]

{
 "keyExplanation": "The acid's negative ion: HI gives I⁻. The base's metal ion: Ca(OH)₂ gives Ca²⁺. Criss-cross the charges: calcium's 2 crosses to the iodide, giving CaI₂. Water forms alongside it."
}

[
 {
  "value": "HNO₃ + NaOH → NaNO₃ + H₂",
  "misconception": "you released hydrogen gas — with a base, the acid's hydrogen ends up in water, not H₂",
  "feedback": null
 },
 {
  "value": "HNO₃ + NaOH → NaNO₃",
  "misconception": "you dropped the water — the acid's H⁺ and the base's OH⁻ pair up and must appear as the product H₂O",
  "feedback": null
 },
 {
  "value": "2HNO₃ + 2NaOH → 2NaNO₃ + 2H₂O",
  "misconception": "your equation is balanced, but not written in the smallest whole-number coefficients — every coefficient here can be divided by two",
  "feedback": null
 }
]

{
 "keyExplanation": "Products: the salt NaNO₃ and water. Count the pairs: one H⁺ from HNO₃, one OH⁻ from NaOH — the counts match, so no coefficients are needed. HNO₃ + NaOH → NaNO₃ + H₂O. Check: 2 H, 1 N, 4 O, 1 Na on each side."
}

[
 {
  "value": 2.72,
  "misconception": "you swapped the two volumes — the unknown's OWN volume is the divisor",
  "feedback": null
 },
 {
  "value": 0.68,
  "misconception": "you assumed the two molarities match — they match only when the two volumes match",
  "feedback": null
 },
 {
  "value": 15.6,
  "misconception": "you multiplied the known side but never divided by the acid's volume",
  "feedback": null
 }
]

{
 "keyExplanation": "Write down the values in the question:\nV(acid) = 92.0 mL\nM(base) = 0.680 M\nV(base) = 23.0 mL\nWrite down the equation:\nM(acid) × V(acid) = M(base) × V(base)\nMake M(acid) the subject:\nM(acid) = M(base) × V(base) ÷ V(acid)\nSubstitute in the values, and calculate:\nM(acid) = 0.680 × 23.0 ÷ 92.0\nM(acid) = 0.170 M\nSanity check: the acid needed four times the base's volume, so it comes out a quarter as concentrated — 0.170 M against 0.680 M passes."
}

[
 {
  "value": 0.142,
  "misconception": "you swapped the two volumes — the unknown's OWN volume is the divisor",
  "feedback": null
 },
 {
  "value": 0.32,
  "misconception": "you assumed the two molarities match — they match only when the two volumes match",
  "feedback": null
 },
 {
  "value": 20.2,
  "misconception": "you multiplied the known side but never divided by the base's volume",
  "feedback": null
 }
]

{
 "keyExplanation": "Write down the values in the question:\nV(base) = 28.0 mL\nM(acid) = 0.320 M\nV(acid) = 63.0 mL\nWrite down the equation:\nM(acid) × V(acid) = M(base) × V(base)\nMake M(base) the subject:\nM(base) = M(acid) × V(acid) ÷ V(base)\nSubstitute in the values, and calculate:\nM(base) = 0.320 × 63.0 ÷ 28.0\nM(base) = 0.720 M\nSanity check: the base needed well under half the acid's volume, so it comes out more than twice as concentrated — 0.720 M against 0.320 M passes."
}