Free balancing equations worksheet | GCSE chemistry | Teachit - Free Printable

Let’s go through each equation one by one and balance them. Balancing means making sure the number of atoms of each element is the same on both sides of the arrow.

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1. C + O₂ → CO₂

Left: 1 C, 2 O
Right: 1 C, 2 O
✔ Already balanced!

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2. H₂ + O₂ → H₂O

Left: 2 H, 2 O
Right: 2 H, 1 O → Not balanced! Oxygen is short on right.

Try putting a 2 in front of H₂O:
H₂ + O₂ → 2H₂O
Now right has 4 H and 2 O → too many H on right.

So put a 2 in front of H₂:
2H₂ + O₂ → 2H₂O
Left: 4 H, 2 O
Right: 4 H, 2 O
✔ Balanced!

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3. Na + H₂O → NaOH + H₂

Left: 1 Na, 2 H, 1 O
Right: 1 Na, 1 O, 1 H (from NaOH) + 2 H (from H₂) = 3 H total → not balanced.

Try 2Na + 2H₂O → 2NaOH + H₂
Left: 2 Na, 4 H, 2 O
Right: 2 Na, 2 O, 2 H (from 2NaOH) + 2 H (from H₂) = 4 H
✔ Balanced!

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4. Na + O₂ → Na₂O

Left: 1 Na, 2 O
Right: 2 Na, 1 O → not balanced.

Need 2 Na on left → try 2Na + O₂ → Na₂O → still oxygen mismatch.

Right has only 1 O, left has 2 → so make 2Na₂O on right? Then need 4 Na on left.

Try: 4Na + O₂ → 2Na₂O
Left: 4 Na, 2 O
Right: 4 Na, 2 O
✔ Balanced!

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5. Na + Cl₂ → NaCl

Left: 1 Na, 2 Cl
Right: 1 Na, 1 Cl → Cl not balanced.

Put 2 in front of NaCl:
Na + Cl₂ → 2NaCl → now 2 Na needed on left.

So: 2Na + Cl₂ → 2NaCl
Left: 2 Na, 2 Cl
Right: 2 Na, 2 Cl
✔ Balanced!

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6. NaOH + HCl → NaCl + H₂O

Left: Na=1, O=1, H=1+1=2, Cl=1
Right: Na=1, Cl=1, H=2, O=1
✔ Already balanced!

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7. NaOH + HNO₃ → NaNO₃ + H₂O

Left: Na=1, O=1+3=4, H=1+1=2, N=1
Right: Na=1, N=1, O=3+1=4, H=2
✔ Already balanced!

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8. NaOH + H₂SO₄ → Na₂SO₄ + H₂O

Left: Na=1, O=1+4=5, H=1+2=3, S=1
Right: Na=2, S=1, O=4+1=5, H=2 → Na and H not balanced.

Need 2 Na on left → try 2NaOH + H₂SO₄ → Na₂SO₄ + H₂O
Left: Na=2, O=2+4=6, H=2+2=4, S=1
Right: Na=2, S=1, O=4+1=5, H=2 → O and H still off.

Water needs to be 2H₂O to match H and O.

Try: 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
Left: Na=2, O=2+4=6, H=2+2=4, S=1
Right: Na=2, S=1, O=4+2=6, H=4
✔ Balanced!

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9. Na₂CO₃ + HCl → NaCl + H₂O + CO₂

Left: Na=2, C=1, O=3, H=1, Cl=1
Right: Na=1, Cl=1, H=2, O=1+2=3, C=1 → Na and H and Cl not balanced.

Need 2 NaCl for 2 Na → so 2HCl to get 2 Cl.

Try: Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂
Left: Na=2, C=1, O=3, H=2, Cl=2
Right: Na=2, Cl=2, H=2, O=1+2=3, C=1
✔ Balanced!

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10. NaOH + CO₂ → Na₂CO₃ + H₂O

Left: Na=1, O=1+2=3, H=1, C=1
Right: Na=2, C=1, O=3+1=4, H=2 → Na, H, O not balanced.

Need 2 NaOH on left → 2NaOH + CO₂ → Na₂CO₃ + H₂O
Left: Na=2, O=2+2=4, H=2, C=1
Right: Na=2, C=1, O=3+1=4, H=2
✔ Balanced!

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Final Answer:

1. C + O₂ → CO₂
2. 2H₂ + O₂ → 2H₂O
3. 2Na + 2H₂O → 2NaOH + H₂
4. 4Na + O₂ → 2Na₂O
5. 2Na + Cl₂ → 2NaCl
6. NaOH + HCl → NaCl + H₂O
7. NaOH + HNO₃ → NaNO₃ + H₂O
8. 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
9. Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂
10. 2NaOH + CO₂ → Na₂CO₃ + H₂O