Printable chemistry worksheet featuring eight problems where students identify reaction types and balance the equations.

Let’s solve each reaction one by one: identify the type of reaction and then balance it.

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1) ___ K + ___ Cl₂ → ___ KCl

Type of Reaction: Synthesis (S) — two elements combine to form a compound.
Balancing:
K is 1 on left, 1 on right → OK
Cl: 2 on left, 1 on right → need 2 KCl
So: 2K + Cl₂ → 2KCl
✔ Balanced equation: 2 K + 1 Cl₂ → 2 KCl

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2) ___ NH₃ → ___ N₂ + ___ H₂

Type of Reaction: Decomposition (D) — one compound breaks into two or more simpler substances.
Balancing:
N: 1 on left, 2 on right → need 2 NH₃
H: 6 on left (2×3), 2 on right → need 3 H₂
So: 2NH₃ → N₂ + 3H₂
✔ Balanced equation: 2 NH₃ → 1 N₂ + 3 H₂

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3) ___ NaF + ___ Br₂ → ___ NaBr + ___ F₂

Type of Reaction: Single Replacement (SR) — one element replaces another in a compound.
But wait — this reaction is not chemically feasible under normal conditions because fluorine (F₂) is more reactive than bromine (Br₂). So Br₂ cannot displace F⁻ from NaF.
However, for the purpose of this worksheet (assuming we’re just practicing balancing and classification), we’ll classify it as SR and balance it as written.

Balancing:
Na: 1 on both sides → OK
F: 1 on left, 2 on right → need 2 NaF
Br: 2 on left, 1 on right → need 2 NaBr
Then F₂: now 2 F on left → 1 F₂ on right
So: 2NaF + Br₂ → 2NaBr + F₂
✔ Balanced equation: 2 NaF + 1 Br₂ → 2 NaBr + 1 F₂

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4) ___ SO₂ + ___ Li₂Se → ___ SSe₂ + ___ Li₂O

Type of Reaction: Double Replacement (DR) — ions swap partners.
SO₂ + Li₂Se → SSe₂ + Li₂O
Check atoms:
S: 1=1
O: 2 on left, 1 on right → need 2 Li₂O
Li: 2 on left, 4 on right → need 2 Li₂Se
Se: 1 on left, 2 on right → need 2 Se → so 2 Li₂Se → gives 2 Se → need 1 SSe₂? Wait, that doesn’t match.

Actually, let’s reassign:
Left: SO₂ (S, 2O) + Li₂Se (2Li, Se)
Right: SSe₂ (S, 2Se) + Li₂O (2Li, O)

This doesn’t balance easily — perhaps there’s a typo? Maybe it should be SO₂ + 2 Li₂Se → SSe₂ + 2 Li₂O?

Check:
Left: S=1, O=2, Li=4, Se=2
Right: S=1, Se=2, Li=4, O=2 → ✔ Balanced!

✔ Balanced equation: 1 SO₂ + 2 Li₂Se → 1 SSe₂ + 2 Li₂O
Type: Double Replacement (DR)

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5) ___ PbSO₄ → ___ PbSO₃ + ___ O₂

Type of Reaction: Decomposition (D) — one compound breaks down.
PbSO₄ → PbSO₃ + O₂
Check atoms:
Pb: 1=1
S: 1=1
O: 4 on left, 3+2=5 on right → not balanced.

Wait — this reaction doesn’t make chemical sense. PbSO₄ doesn’t decompose to PbSO₃ + O₂. But again, for worksheet purposes, we’ll try to balance as written.

Left: PbSO₄ → Right: PbSO₃ + O₂
Oxygen: 4 vs 3+2=5 → mismatch.

Maybe it’s supposed to be 2PbSO₄ → 2PbSO₃ + O₂?
Left: Pb=2, S=2, O=8
Right: Pb=2, S=2, O=6+2=8 → ✔ YES!

✔ Balanced equation: 2 PbSO₄ → 2 PbSO₃ + 1 O₂
Type: Decomposition (D)

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6) ___ Al + ___ Fe₂O₃ → ___ Fe + ___ Al₂O₃

Type of Reaction: Single Replacement (SR) — aluminum displaces iron (thermite reaction).
Balancing:
Al: 1 on left, 2 on right → need 2 Al
Fe: 2 on left, 1 on right → need 2 Fe
O: 3 on left, 3 on right → OK
So: 2Al + Fe₂O₃ → 2Fe + Al₂O₃
✔ Balanced equation: 2 Al + 1 Fe₂O₃ → 2 Fe + 1 Al₂O₃

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7) ___ SF₆ → ___ S + ___ F₂

Type of Reaction: Decomposition (D) — one compound breaks into elements.
Balancing:
S: 1=1
F: 6 on left → need 3 F₂ on right
✔ Balanced equation: 1 SF₆ → 1 S + 3 F₂

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8) ___ C₂H₄ + ___ O₂ → ___ CO₂ + ___ H₂O

Type of Reaction: Combustion (C) — hydrocarbon reacts with oxygen to produce CO₂ and H₂O.
Balancing:
C: 2 on left → need 2 CO₂
H: 4 on left → need 2 H₂O
O: on right: 2×2 + 2×1 = 6 → need 3 O₂ on left
✔ Balanced equation: 1 C₂H₄ + 3 O₂ → 2 CO₂ + 2 H₂O

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## ✔ Final Answers:

1) 2 K + 1 Cl₂ → 2 KCl — S
2) 2 NH₃ → 1 N₂ + 3 H₂ — D
3) 2 NaF + 1 Br₂ → 2 NaBr + 1 F₂ — SR
4) 1 SO₂ + 2 Li₂Se → 1 SSe₂ + 2 Li₂O — DR
5) 2 PbSO₄ → 2 PbSO₃ + 1 O₂ — D
6) 2 Al + 1 Fe₂O₃ → 2 Fe + 1 Al₂O₃ — SR
7) 1 SF₆ → 1 S + 3 F₂ — D
8) 1 C₂H₄ + 3 O₂ → 2 CO₂ + 2 H₂O — C

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📌 Note: Some reactions (like #3 and #5) are not thermodynamically favorable in reality, but for educational purposes, we classified and balanced them as written. Always verify real-world feasibility in advanced chemistry!