Balancing Chemical Equations Worksheet - Free Printable

To balance these chemical equations, we need to make sure that the number of atoms of each element is the same on both sides of the reaction arrow. We do this by adding coefficients (numbers) in front of the chemical formulas. We never change the subscripts (the small numbers inside the formulas).

Here is the step-by-step balancing for each equation:

1. Iron + Sulfuric Acid
* Unbalanced: Fe + H₂SO₄ → Fe₂(SO₄)₃ + H₂
* Step 1: Balance Iron (Fe). There are 2 Fe on the right, so we need 2 on the left.
* 2 Fe + H₂SO₄ → Fe₂(SO₄)₃ + H₂
* Step 2: Balance Sulfate (SO₄). There are 3 SO₄ groups on the right, so we need 3 on the left.
* 2 Fe + 3 H₂SO₄ → Fe₂(SO₄)₃ + H₂
* Step 3: Balance Hydrogen (H). There are 6 H on the left (3 × 2), so we need 6 on the right. We put a 3 in front of H₂.
* 2 Fe + 3 H₂SO₄ → Fe₂(SO₄)₃ + 3 H₂
* Check: 2 Fe, 6 H, 3 S, 12 O on both sides. Balanced.

2. Methane Combustion
* Unbalanced: CH₄ + O₂ → CO₂ + H₂O
* Step 1: Balance Carbon (C). 1 on left, 1 on right. Good.
* Step 2: Balance Hydrogen (H). 4 on left, 2 on right. Put a 2 in front of H₂O.
* CH₄ + O₂ → CO₂ + 2 H₂O
* Step 3: Balance Oxygen (O). There are 4 O on the right (2 from CO₂ + 2 from 2H₂O). We need 4 on the left. Put a 2 in front of O₂.
* CH₄ + 2 O₂ → CO₂ + 2 H₂O
* Check: 1 C, 4 H, 4 O on both sides. Balanced.

3. Silicon Tetrachloride Hydrolysis
* Unbalanced: SiCl₄ + H₂O → SiO₂ + HCl
* Step 1: Balance Silicon (Si). 1 on left, 1 on right. Good.
* Step 2: Balance Chlorine (Cl). 4 on left, 1 on right. Put a 4 in front of HCl.
* SiCl₄ + H₂O → SiO₂ + 4 HCl
* Step 3: Balance Hydrogen (H). 4 H on right, 2 H on left. Put a 2 in front of H₂O.
* SiCl₄ + 2 H₂O → SiO₂ + 4 HCl
* Step 4: Check Oxygen (O). 2 on left, 2 on right. Good.
* Check: 1 Si, 4 Cl, 4 H, 2 O on both sides. Balanced.

4. Silver Iodide + Sodium Sulfide
* Unbalanced: AgI + Na₂S → Ag₂S + NaI
* Step 1: Balance Silver (Ag). 2 on right, 1 on left. Put a 2 in front of AgI.
* 2 AgI + Na₂S → Ag₂S + NaI
* Step 2: Balance Sodium (Na). 2 on left, 1 on right. Put a 2 in front of NaI.
* 2 AgI + Na₂S → Ag₂S + 2 NaI
* Step 3: Check Iodine (I) and Sulfur (S). I: 2 left, 2 right. S: 1 left, 1 right. Good.
* Check: 2 Ag, 2 I, 2 Na, 1 S on both sides. Balanced.

5. Ammonia Oxidation
* Unbalanced: NH₃ + O₂ → NO + H₂O
* Step 1: Balance Hydrogen (H). 3 on left, 2 on right. The common multiple is 6. Put a 2 in front of NH₃ and a 3 in front of H₂O.
* 2 NH₃ + O₂ → NO + 3 H₂O
* Step 2: Balance Nitrogen (N). 2 on left, 1 on right. Put a 2 in front of NO.
* 2 NH₃ + O₂ → 2 NO + 3 H₂O
* Step 3: Balance Oxygen (O). Right side has 5 O (2 from 2NO + 3 from 3H₂O). Left has 2. To get 5, we need 2.5 O₂. Since we usually want whole numbers, multiply everything by 2.
* 4 NH₃ + 5 O₂ → 4 NO + 6 H₂O
* Check: 4 N, 12 H, 10 O on both sides. Balanced.

6. Iron(III) Oxide Reduction
* Unbalanced: FeO₃ + CO → Fe + CO₂
*(Note: The image writes FeO₃, which is chemically unusual compared to Fe₂O₃, but we must balance exactly what is written).*
* Step 1: Balance Oxygen (O). Left has 3 from FeO₃ + 1 from CO = 4 total? No, let's look at the transfer. CO takes one O to become CO₂. FeO₃ has 3 O's to give. So we need 3 CO molecules to take all 3 oxygens.
* FeO₃ + 3 CO → Fe + 3 CO₂
* Step 2: Balance Iron (Fe). 1 on left, 1 on right. Good.
* Step 3: Check Carbon (C). 3 on left, 3 on right. Good.
* Check: 1 Fe, 6 O, 3 C on both sides. Balanced.

7. Silicon Dioxide + Hydrofluoric Acid
* Unbalanced: SiO₂ + HF → SiF₄ + H₂O
* Step 1: Balance Silicon (Si). 1 on left, 1 on right. Good.
* Step 2: Balance Fluorine (F). 4 on right, 1 on left. Put a 4 in front of HF.
* SiO₂ + 4 HF → SiF₄ + H₂O
* Step 3: Balance Hydrogen (H). 4 on left, 2 on right. Put a 2 in front of H₂O.
* SiO₂ + 4 HF → SiF₄ + 2 H₂O
* Step 4: Check Oxygen (O). 2 on left, 2 on right. Good.
* Check: 1 Si, 4 F, 4 H, 2 O on both sides. Balanced.

8. Sodium Bromide + Chlorine
* Unbalanced: NaBr + Cl₂ → NaCl + Br₂
* Step 1: Balance Bromine (Br). 2 on right, 1 on left. Put a 2 in front of NaBr.
* 2 NaBr + Cl₂ → NaCl + Br₂
* Step 2: Balance Sodium (Na). 2 on left, 1 on right. Put a 2 in front of NaCl.
* 2 NaBr + Cl₂ → 2 NaCl + Br₂
* Step 3: Check Chlorine (Cl). 2 on left, 2 on right. Good.
* Check: 2 Na, 2 Br, 2 Cl on both sides. Balanced.

9. Ammonium Phosphate + Lead(IV) Nitrate
* Unbalanced: (NH₄)₃PO₄ + Pb(NO₃)₄ → Pb₃(PO₄)₄ + NH₄NO₃
* Step 1: Balance Lead (Pb). 3 on right, 1 on left. Put a 3 in front of Pb(NO₃)₄.
* (NH₄)₃PO₄ + 3 Pb(NO₃)₄ → Pb₃(PO₄)₄ + NH₄NO₃
* Step 2: Balance Phosphate (PO₄). 4 on right, 1 on left. Put a 4 in front of (NH₄)₃PO₄.
* 4 (NH₄)₃PO₄ + 3 Pb(NO₃)₄ → Pb₃(PO₄)₄ + NH₄NO₃
* Step 3: Balance Ammonium (NH₄) and Nitrate (NO₃).
* Left side NH₄: 4 × 3 = 12.
* Left side NO₃: 3 × 4 = 12.
* Right side needs 12 NH₄ and 12 NO₃ combined. The product is NH₄NO₃, which has one of each. So we need 12 of them.
* 4 (NH₄)₃PO₄ + 3 Pb(NO₃)₄ → Pb₃(PO₄)₄ + 12 NH₄NO₃
* Check: 12 N (in ammonium), 12 H (in ammonium) x 4 = 48 H... wait. Let's count atoms.
* N: 4*3 + 3*4 = 24 on left. Right: 12*2 = 24.
* H: 4*12 = 48 on left. Right: 12*4 = 48.
* P: 4 on left, 4 on right.
* Pb: 3 on left, 3 on right.
* O: 4*4 + 3*12 = 16 + 36 = 52 on left. Right: 4*4 + 12*3 = 16 + 36 = 52.
* Balanced.

10. Magnesium Hydroxide + Hydrochloric Acid
* Unbalanced: Mg(OH)₂ + HCl → MgCl₂ + H₂O
* Step 1: Balance Magnesium (Mg). 1 on left, 1 on right. Good.
* Step 2: Balance Chlorine (Cl). 2 on right, 1 on left. Put a 2 in front of HCl.
* Mg(OH)₂ + 2 HCl → MgCl₂ + H₂O
* Step 3: Balance Hydrogen (H). Left: 2 (from OH) + 2 (from HCl) = 4. Right: 2. Put a 2 in front of H₂O.
* Mg(OH)₂ + 2 HCl → MgCl₂ + 2 H₂O
* Step 4: Check Oxygen (O). 2 on left, 2 on right. Good.
* Check: 1 Mg, 2 O, 4 H, 2 Cl on both sides. Balanced.

Final Answer:
1. 2 Fe + 3 H₂SO₄ → 1 Fe₂(SO₄)₃ + 3 H₂
2. 1 CH₄ + 2 O₂ → 1 CO₂ + 2 H₂O
3. 1 SiCl₄ + 2 H₂O → 1 SiO₂ + 4 HCl
4. 2 AgI + 1 Na₂S → 1 Ag₂S + 2 NaI
5. 4 NH₃ + 5 O₂ → 4 NO + 6 H₂O
6. 1 FeO₃ + 3 CO → 1 Fe + 3 CO₂
7. 1 SiO₂ + 4 HF → 1 SiF₄ + 2 H₂O
8. 2 NaBr + 1 Cl₂ → 2 NaCl + 1 Br₂
9. 4 (NH₄)₃PO₄ + 3 Pb(NO₃)₄ → 1 Pb₃(PO₄)₄ + 12 NH₄NO₃
10. 1 Mg(OH)₂ + 2 HCl → 1 MgCl₂ + 2 H₂O