Practice worksheet for writing and balancing chemical reactions, featuring ten word problems involving various chemical substances and reactions.

Let’s go through each reaction one by one. We’ll write the correct chemical formulas first, then balance them so that the number of atoms of each element is the same on both sides.

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1) Solid aluminum reacts with oxygen gas to produce solid aluminum oxide.

- Aluminum = Al (solid)
- Oxygen gas = O₂ (gas)
- Aluminum oxide = Al₂O₃ (solid)

Unbalanced:
Al + O₂ → Al₂O₃

Balance:
- Right side has 2 Al, left has 1 → put 4 Al on left
- Right side has 3 O, left has 2 → need 6 O on both sides → use 3 O₂ on left, and 2 Al₂O₃ on right? Wait — let’s do it step by step.

Try:
4Al + 3O₂ → 2Al₂O₃
Check:
Left: 4 Al, 6 O
Right: 4 Al, 6 O → ✔ Balanced!

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2) Propane reacts with oxygen to produce carbon dioxide and water.

Propane = C₃H₈
Oxygen = O₂
Carbon dioxide = CO₂
Water = H₂O

Unbalanced:
C₃H₈ + O₂ → CO₂ + H₂O

Balance:
- Carbon: 3 on left → 3 CO₂ on right
- Hydrogen: 8 on left → 4 H₂O on right (since each has 2 H)
- Now oxygen: right side = 3×2 + 4×1 = 6 + 4 = 10 O → so need 5 O₂ on left

Balanced:
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
Check:
Left: 3 C, 8 H, 10 O
Right: 3 C, 8 H, 10 O → ✔

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3) Aluminum nitrate reacts with sodium hydroxide to form aluminum hydroxide and sodium nitrate.

Aluminum nitrate = Al(NO₃)₃
Sodium hydroxide = NaOH
Aluminum hydroxide = Al(OH)₃
Sodium nitrate = NaNO₃

Unbalanced:
Al(NO₃)₃ + NaOH → Al(OH)₃ + NaNO₃

Balance:
- Al: 1 on each side → OK
- NO₃: 3 on left → need 3 NaNO₃ on right
- So now Na: 3 on right → need 3 NaOH on left
- OH: 3 on left → matches Al(OH)₃ on right

Balanced:
Al(NO₃)₃ + 3NaOH → Al(OH)₃ + 3NaNO₃
Check:
Left: Al=1, N=3, O=9+3=12, Na=3, H=3
Right: Al=1, O=3+9=12, H=3, Na=3, N=3 → ✔

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4) Potassium nitrate decomposes to form potassium nitrite and oxygen.

Potassium nitrate = KNO₃
Potassium nitrite = KNO₂
Oxygen = O₂

Unbalanced:
KNO₃ → KNO₂ + O₂

Balance:
- K and N are balanced (1 each side)
- Oxygen: left=3, right=2+2=4? Wait — KNO₂ has 2 O, O₂ has 2 → total 4? No, we need to adjust coefficients.

Try 2KNO₃ → 2KNO₂ + O₂
Left: 2K, 2N, 6O
Right: 2K, 2N, 4O (from 2KNO₂) + 2O (from O₂) = 6O → ✔

Balanced:
2KNO₃ → 2KNO₂ + O₂

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5) Oxygen reacts with carbon sulfide to form carbon dioxide and sulfur dioxide.

“Carbon sulfide” likely means carbon disulfide = CS₂
Oxygen = O₂
Carbon dioxide = CO₂
Sulfur dioxide = SO₂

Unbalanced:
CS₂ + O₂ → CO₂ + SO₂

Balance:
- C: 1 each → OK
- S: 2 on left → need 2 SO₂ on right
- Now O: right = 2 (from CO₂) + 4 (from 2SO₂) = 6 → so need 3 O₂ on left

Balanced:
CS₂ + 3O₂ → CO₂ + 2SO₂
Check:
Left: C=1, S=2, O=6
Right: C=1, S=2, O=2+4=6 → ✔

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6) Potassium chlorate decomposes to form potassium chloride and oxygen.

Potassium chlorate = KClO₃
Potassium chloride = KCl
Oxygen = O₂

Unbalanced:
KClO₃ → KCl + O₂

Balance:
- K and Cl: 1 each → OK
- O: 3 on left, 2 on right → find LCM of 3 and 2 = 6

So: 2KClO₃ → 2KCl + 3O₂
Left: 2K, 2Cl, 6O
Right: 2K, 2Cl, 6O → ✔

Balanced:
2KClO₃ → 2KCl + 3O₂

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7) Barium fluoride reacts with potassium phosphate to form barium phosphate and potassium fluoride.

Barium fluoride = BaF₂
Potassium phosphate = K₃PO₄
Barium phosphate = Ba₃(PO₄)₂
Potassium fluoride = KF

Unbalanced:
BaF₂ + K₃PO₄ → Ba(PO₄)₂ + KF

Balance:
- Ba: 1 vs 3 → need 3 BaF₂ on left
- PO₄: 1 vs 2 → need 2 K₃PO₄ on left
- Now K: 2×3=6 on left → need 6 KF on right
- F: 3×2=6 on left → 6 KF on right → matches

Balanced:
3BaF₂ + 2K₃PO₄ → Ba₃(PO₄)₂ + 6KF
Check:
Left: Ba=3, F=6, K=6, P=2, O=8
Right: Ba=3, P=2, O=8, K=6, F=6 → ✔

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8) Hydrogen sulfate reacts with magnesium nitrate to form magnesium sulfate and hydrogen nitrate.

Hydrogen sulfate = H₂SO₄
Magnesium nitrate = Mg(NO₃)₂
Magnesium sulfate = MgSO₄
Hydrogen nitrate = HNO₃

Unbalanced:
H₂SO₄ + Mg(NO₃)₂ → MgSO₄ + HNO₃

Balance:
- Mg: 1 each → OK
- SO₄: 1 each → OK
- NO₃: 2 on left → need 2 HNO₃ on right
- H: 2 on left → 2 HNO₃ on right → matches

Balanced:
H₂SO₄ + Mg(NO₃)₂ → MgSO₄ + 2HNO₃
Check:
Left: H=2, S=1, O=4+6=10, Mg=1, N=2
Right: Mg=1, S=1, O=4+6=10, H=2, N=2 → ✔

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9) Solid aluminum reacts with hydrogen sulfate to form aluminum sulfate and hydrogen.

Aluminum = Al
Hydrogen sulfate = H₂SO₄
Aluminum sulfate = Al₂(SO₄)
Hydrogen = H₂

Unbalanced:
Al + H₂SO₄ → Al₂(SO₄)₃ + H₂

Balance:
- Al: 1 vs 2 → need 2 Al on left
- SO₄: 1 vs 3 → need 3 H₂SO₄ on left
- H: 3×2=6 on left → need 3 H₂ on right

Balanced:
2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂
Check:
Left: Al=2, H=6, S=3, O=12
Right: Al=2, S=3, O=12, H=6 → ✔

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10) Tungsten oxide reacts with hydrogen to form tungsten and water.

Tungsten oxide — assume WO₃ (common form)
Hydrogen = H₂
Tungsten = W
Water = H₂O

Unbalanced:
WO₃ + H₂ → W + H₂O

Balance:
- W: 1 each → OK
- O: 3 on left → need 3 H₂O on right
- H: 3×2=6 on right → need 3 H₂ on left

Balanced:
WO₃ + 3H₂ → W + 3H₂O
Check:
Left: W=1, O=3, H=6
Right: W=1, H=6, O=3 → ✔

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Final Answer:

1) 4Al + 3O₂ → 2Al₂O₃
2) C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
3) Al(NO₃)₃ + 3NaOH → Al(OH)₃ + 3NaNO₃
4) 2KNO₃ → 2KNO₂ + O₂
5) CS₂ + 3O₂ → CO₂ + 2SO₂
6) 2KClO₃ → 2KCl + 3O₂
7) 3BaF₂ + 2K₃PO₄ → Ba₃(PO₄)₂ + 6KF
8) H₂SO₄ + Mg(NO₃)₂ → MgSO₄ + 2HNO₃
9) 2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂
10) WO₃ + 3H₂ → W + 3H₂O