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Chemical Equation Balancer worksheet

Grades 9–10

Solve each problem and show your work. Round answers to 2 decimal places where needed.

  1. Problem 1.
    • Unbalanced equation: C4H1 + O3 -> CO4 + H4O

    Find: Balanced equation

  2. Problem 2.
    • Unbalanced equation: C2H10 + O3 -> CO2 + H4O

    Find: Balanced equation

  3. Problem 3.
    • Unbalanced equation: C3H8 + O1 -> CO2 + H1O

    Find: Balanced equation

  4. Problem 4.
    • Unbalanced equation: C1H8 + O1 -> CO2 + H4O

    Find: Balanced equation

  5. Problem 5.
    • Unbalanced equation: C2H4 + O1 -> CO2 + H3O

    Find: Balanced equation

  6. Problem 6.
    • Unbalanced equation: C5H5 + O1 -> CO3 + H3O

    Find: Balanced equation

  7. Problem 7.
    • Unbalanced equation: C5H4 + O3 -> CO2 + H4O

    Find: Balanced equation

  8. Problem 8.
    • Unbalanced equation: C6H4 + O4 -> CO1 + H2O

    Find: Balanced equation

  9. Problem 9.
    • Unbalanced equation: C3H4 + O1 -> CO3 + H3O

    Find: Balanced equation

  10. Problem 10.
    • Unbalanced equation: C1H5 + O1 -> CO3 + H4O

    Find: Balanced equation

Answer key: Chemical Equation Balancer worksheet

  1. 1. Balanced equation: 12C₄H₁ + 65O₃ → 48CO₄ + 3H₄O

    1. Give each substance an unknown number (coefficient) to find

      a C₄H₁ + b O₃ → c CO₄ + d H₄O
    2. Atoms are never lost or gained, so the C atoms must match on both sides

      C: 4a = c
    3. Atoms are never lost or gained, so the H atoms must match on both sides

      H: a = 4d
    4. Atoms are never lost or gained, so the O atoms must match on both sides

      O: 3b = 4c + d
    5. Solve these 3 equations together, using exact fractions. One of them can be anything, so pick it to make all of them the smallest whole numbers

      a : b : c : d = 12 : 65 : 48 : 3
    6. Check the answer: count every element's atoms on each side

      C: 48 = 48, H: 12 = 12, O: 195 = 195
    7. The balanced equation

      12C₄H₁ + 65O₃ → 48CO₄ + 3H₄O
  2. 2. Balanced equation: 6C₂H₁₀ + 13O₃ → 12CO₂ + 15H₄O

    1. Give each substance an unknown number (coefficient) to find

      a C₂H₁₀ + b O₃ → c CO₂ + d H₄O
    2. Atoms are never lost or gained, so the C atoms must match on both sides

      C: 2a = c
    3. Atoms are never lost or gained, so the H atoms must match on both sides

      H: 10a = 4d
    4. Atoms are never lost or gained, so the O atoms must match on both sides

      O: 3b = 2c + d
    5. Solve these 3 equations together, using exact fractions. One of them can be anything, so pick it to make all of them the smallest whole numbers

      a : b : c : d = 6 : 13 : 12 : 15
    6. Check the answer: count every element's atoms on each side

      C: 12 = 12, H: 60 = 60, O: 39 = 39
    7. The balanced equation

      6C₂H₁₀ + 13O₃ → 12CO₂ + 15H₄O
  3. 3. Balanced equation: C₃H₈ + 14O₁ → 3CO₂ + 8H₁O

    1. Give each substance an unknown number (coefficient) to find

      a C₃H₈ + b O₁ → c CO₂ + d H₁O
    2. Atoms are never lost or gained, so the C atoms must match on both sides

      C: 3a = c
    3. Atoms are never lost or gained, so the H atoms must match on both sides

      H: 8a = d
    4. Atoms are never lost or gained, so the O atoms must match on both sides

      O: b = 2c + d
    5. Solve these 3 equations together, using exact fractions. One of them can be anything, so pick it to make all of them the smallest whole numbers

      a : b : c : d = 1 : 14 : 3 : 8
    6. Check the answer: count every element's atoms on each side

      C: 3 = 3, H: 8 = 8, O: 14 = 14
    7. The balanced equation

      C₃H₈ + 14O₁ → 3CO₂ + 8H₁O
  4. 4. Balanced equation: C₁H₈ + 4O₁ → CO₂ + 2H₄O

    1. Give each substance an unknown number (coefficient) to find

      a C₁H₈ + b O₁ → c CO₂ + d H₄O
    2. Atoms are never lost or gained, so the C atoms must match on both sides

      C: a = c
    3. Atoms are never lost or gained, so the H atoms must match on both sides

      H: 8a = 4d
    4. Atoms are never lost or gained, so the O atoms must match on both sides

      O: b = 2c + d
    5. Solve these 3 equations together, using exact fractions. One of them can be anything, so pick it to make all of them the smallest whole numbers

      a : b : c : d = 1 : 4 : 1 : 2
    6. Check the answer: count every element's atoms on each side

      C: 1 = 1, H: 8 = 8, O: 4 = 4
    7. The balanced equation

      C₁H₈ + 4O₁ → CO₂ + 2H₄O
  5. 5. Balanced equation: 3C₂H₄ + 16O₁ → 6CO₂ + 4H₃O

    1. Give each substance an unknown number (coefficient) to find

      a C₂H₄ + b O₁ → c CO₂ + d H₃O
    2. Atoms are never lost or gained, so the C atoms must match on both sides

      C: 2a = c
    3. Atoms are never lost or gained, so the H atoms must match on both sides

      H: 4a = 3d
    4. Atoms are never lost or gained, so the O atoms must match on both sides

      O: b = 2c + d
    5. Solve these 3 equations together, using exact fractions. One of them can be anything, so pick it to make all of them the smallest whole numbers

      a : b : c : d = 3 : 16 : 6 : 4
    6. Check the answer: count every element's atoms on each side

      C: 6 = 6, H: 12 = 12, O: 16 = 16
    7. The balanced equation

      3C₂H₄ + 16O₁ → 6CO₂ + 4H₃O
  6. 6. Balanced equation: 3C₅H₅ + 50O₁ → 15CO₃ + 5H₃O

    1. Give each substance an unknown number (coefficient) to find

      a C₅H₅ + b O₁ → c CO₃ + d H₃O
    2. Atoms are never lost or gained, so the C atoms must match on both sides

      C: 5a = c
    3. Atoms are never lost or gained, so the H atoms must match on both sides

      H: 5a = 3d
    4. Atoms are never lost or gained, so the O atoms must match on both sides

      O: b = 3c + d
    5. Solve these 3 equations together, using exact fractions. One of them can be anything, so pick it to make all of them the smallest whole numbers

      a : b : c : d = 3 : 50 : 15 : 5
    6. Check the answer: count every element's atoms on each side

      C: 15 = 15, H: 15 = 15, O: 50 = 50
    7. The balanced equation

      3C₅H₅ + 50O₁ → 15CO₃ + 5H₃O
  7. 7. Balanced equation: 3C₅H₄ + 11O₃ → 15CO₂ + 3H₄O

    1. Give each substance an unknown number (coefficient) to find

      a C₅H₄ + b O₃ → c CO₂ + d H₄O
    2. Atoms are never lost or gained, so the C atoms must match on both sides

      C: 5a = c
    3. Atoms are never lost or gained, so the H atoms must match on both sides

      H: 4a = 4d
    4. Atoms are never lost or gained, so the O atoms must match on both sides

      O: 3b = 2c + d
    5. Solve these 3 equations together, using exact fractions. One of them can be anything, so pick it to make all of them the smallest whole numbers

      a : b : c : d = 3 : 11 : 15 : 3
    6. Check the answer: count every element's atoms on each side

      C: 15 = 15, H: 12 = 12, O: 33 = 33
    7. The balanced equation

      3C₅H₄ + 11O₃ → 15CO₂ + 3H₄O
  8. 8. Balanced equation: C₆H₄ + 2O₄ → 6CO₁ + 2H₂O

    1. Give each substance an unknown number (coefficient) to find

      a C₆H₄ + b O₄ → c CO₁ + d H₂O
    2. Atoms are never lost or gained, so the C atoms must match on both sides

      C: 6a = c
    3. Atoms are never lost or gained, so the H atoms must match on both sides

      H: 4a = 2d
    4. Atoms are never lost or gained, so the O atoms must match on both sides

      O: 4b = c + d
    5. Solve these 3 equations together, using exact fractions. One of them can be anything, so pick it to make all of them the smallest whole numbers

      a : b : c : d = 1 : 2 : 6 : 2
    6. Check the answer: count every element's atoms on each side

      C: 6 = 6, H: 4 = 4, O: 8 = 8
    7. The balanced equation

      C₆H₄ + 2O₄ → 6CO₁ + 2H₂O
  9. 9. Balanced equation: 3C₃H₄ + 31O₁ → 9CO₃ + 4H₃O

    1. Give each substance an unknown number (coefficient) to find

      a C₃H₄ + b O₁ → c CO₃ + d H₃O
    2. Atoms are never lost or gained, so the C atoms must match on both sides

      C: 3a = c
    3. Atoms are never lost or gained, so the H atoms must match on both sides

      H: 4a = 3d
    4. Atoms are never lost or gained, so the O atoms must match on both sides

      O: b = 3c + d
    5. Solve these 3 equations together, using exact fractions. One of them can be anything, so pick it to make all of them the smallest whole numbers

      a : b : c : d = 3 : 31 : 9 : 4
    6. Check the answer: count every element's atoms on each side

      C: 9 = 9, H: 12 = 12, O: 31 = 31
    7. The balanced equation

      3C₃H₄ + 31O₁ → 9CO₃ + 4H₃O
  10. 10. Balanced equation: 4C₁H₅ + 17O₁ → 4CO₃ + 5H₄O

    1. Give each substance an unknown number (coefficient) to find

      a C₁H₅ + b O₁ → c CO₃ + d H₄O
    2. Atoms are never lost or gained, so the C atoms must match on both sides

      C: a = c
    3. Atoms are never lost or gained, so the H atoms must match on both sides

      H: 5a = 4d
    4. Atoms are never lost or gained, so the O atoms must match on both sides

      O: b = 3c + d
    5. Solve these 3 equations together, using exact fractions. One of them can be anything, so pick it to make all of them the smallest whole numbers

      a : b : c : d = 4 : 17 : 4 : 5
    6. Check the answer: count every element's atoms on each side

      C: 4 = 4, H: 20 = 20, O: 17 = 17
    7. The balanced equation

      4C₁H₅ + 17O₁ → 4CO₃ + 5H₄O