Chemical reactions worksheet focusing on balancing equations and identifying single and double displacement reactions.

Let’s go step by step through each equation. We’ll balance them first, then decide if it’s SINGLE or DOUBLE displacement.

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What is single vs double displacement?

- Single displacement: One element replaces another in a compound.
Example: A + BC → AC + B
(One free element kicks out another from a compound)

- Double displacement: Two compounds swap partners.
Example: AB + CD → AD + CB
(Both sides have two elements swapping places)

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Now let’s solve each one:

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1) ___ Cl₂ + ___ KI → ___ KCl + ___ I₂

Chlorine (Cl₂) is replacing iodine in KI → so chlorine becomes part of KCl, and iodine is freed as I₂.

Balance:
Left: Cl=2, K=1, I=1
Right: K=1, Cl=1, I=2

We need 2 KI to get 2 I on left → makes 2 K and 2 I
Then we need 2 KCl on right to match 2 K and 2 Cl
But Cl₂ already gives 2 Cl → perfect.

So:
1 Cl₂ + 2 KI → 2 KCl + 1 I₂

Type: Single displacement (Cl replaces I)

→ SINGLE

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2) ___ K₂CO₃ + ___ BaCl₂ → ___ KCl + ___ BaCO₃

Two compounds: K₂CO₃ and BaCl₂ → they swap partners: K with Cl, Ba with CO₃

This is classic double displacement.

Balance:
Left: K=2, C=1, O=3, Ba=1, Cl=2
Right: K=1, Cl=1, Ba=1, C=1, O=3

Need 2 KCl on right to match 2 K and 2 Cl.

So:
1 K₂CO₃ + 1 BaCl₂ → 2 KCl + 1 BaCO₃

Type: Double displacement

→ DOUBLE

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3) ___ Na + ___ MgCl₂ → ___ NaCl + ___ Mg

Na is an element, MgCl₂ is a compound → Na will try to replace Mg.

Check activity series: Sodium is more reactive than magnesium? Actually, no — wait! In reality, sodium is MORE reactive than magnesium? Let me think...

Actually, in the reactivity series:
K > Na > Ca > Mg > Al > Zn > Fe > Sn > Pb > H > Cu > Ag > Au

So Na is ABOVE Mg → yes, Na can displace Mg.

So this is single displacement.

Balance:
Left: Na=1, Mg=1, Cl=2
Right: Na=1, Cl=1, Mg=1 → need 2 NaCl to get 2 Cl

So put 2 Na on left, 2 NaCl on right.

2 Na + 1 MgCl₂ → 2 NaCl + 1 Mg

Type: Single displacement

→ SINGLE

*(Note: Even though in real lab conditions this might not happen easily due to water etc., for worksheet purposes, we assume based on reactivity series.)*

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4) ___ Al + ___ CuCl₂ → ___ AlCl₃ + ___ Cu

Aluminum replaces copper → single displacement.

Balance:
Left: Al=1, Cu=1, Cl=2
Right: Al=1, Cl=3, Cu=1 → mismatch in Cl

Find LCM of 2 and 3 → 6

So:
3 CuCl₂ → 6 Cl → needs 2 AlCl₃ (which has 6 Cl)
Then Al: 2 on right → need 2 on left
Cu: 3 on left → need 3 on right

So:
2 Al + 3 CuCl₂ → 2 AlCl₃ + 3 Cu

Type: Single displacement

→ SINGLE

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5) ___ Al + ___ Pb(NO₃)₂ → ___ Al(NO₃)₃ + ___ Pb

Al replaces Pb → single displacement.

Balance:
Left: Al=1, Pb=1, N=2, O=6
Right: Al=1, N=3, O=9, Pb=1 → mismatch in NO₃ groups

LCM of 2 and 3 is 6.

So:
3 Pb(NO₃)₂ → 6 NO₃ → needs 2 Al(NO₃)₃ (which has 6 NO₃)
Then Al: 2 on right → need 2 on left
Pb: 3 on left → need 3 on right

So:
2 Al + 3 Pb(NO₃)₂ → 2 Al(NO₃)₃ + 3 Pb

Type: Single displacement

→ SINGLE

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6) ___ AgNO₃ + ___ CaBr₂ → ___ AgBr + ___ Ca(NO₃)₂

Two compounds → likely double displacement.

Ag swaps with Ca? Wait: AgNO₃ and CaBr₂ → Ag pairs with Br, Ca pairs with NO₃.

Yes → double displacement.

Balance:
Left: Ag=1, N=1, O=3, Ca=1, Br=2
Right: Ag=1, Br=1, Ca=1, N=2, O=6 → mismatch

Need 2 AgNO₃ to get 2 NO₃ → then Ca(NO₃)₂ takes care of that.

Then 2 AgBr needed for 2 Ag and 2 Br.

CaBr₂ already has 2 Br → good.

So:
2 AgNO₃ + 1 CaBr₂ → 2 AgBr + 1 Ca(NO₃)₂

Type: Double displacement

→ DOUBLE

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7) ___ Al₂(SO₄)₃ + ___ Ca₃(PO₄)₂ → ___ AlPO₄ + ___ CaSO₄

Two compounds → double displacement.

Swap: Al with PO₄, Ca with SO₄

Balance carefully.

Left:
Al=2, S=3, O from SO₄: 12, plus PO₄: P=2, O=8 → total O complicated, better count ions.

Better approach: treat polyatomic ions as units.

Al₂(SO₄)₃ → 2 Al³⁺, 3 SO₄²⁻
Ca(PO₄)₂ → 3 Ca²⁺, 2 PO₄³⁻

Products: AlPO₄ and CaSO₄

To balance charges and atoms:

Try coefficients:

Suppose we take 1 Al₂(SO₄)₃ and 1 Ca₃(PO₄)₂

Gives: 2 Al, 3 SO₄, 3 Ca, 2 PO₄

Want to make AlPO₄ and CaSO₄.

Each AlPO₄ uses 1 Al and 1 PO₄ → so 2 AlPO₄ would use 2 Al and 2 PO₄ → matches!

Each CaSO₄ uses 1 Ca and 1 SO₄ → we have 3 Ca and 3 SO₄ → so 3 CaSO₄.

Perfect!

So:
1 Al₂(SO₄)₃ + 1 Ca₃(PO)₂ → 2 AlPO₄ + 3 CaSO₄

Type: Double displacement

→ DOUBLE

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8) ___ FeBr₂ + ___ K₂CO₃ → ___ FeCO₃ + ___ KBr

Two compounds → double displacement.

Fe swaps with K? No: FeBr₂ and K₂CO₃ → Fe pairs with CO₃, K pairs with Br.

Yes.

Balance:
Left: Fe=1, Br=2, K=2, C=1, O=3
Right: Fe=1, C=1, O=3, K=1, Br=1 → need 2 KBr

So:
1 FeBr₂ + 1 K₂CO₃ → 1 FeCO₃ + 2 KBr

Type: Double displacement

→ DOUBLE

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9) ___ Cu + ___ Ag₂SO₄ → ___ Ag + ___ CuSO₄

Cu is element, Ag₂SO₄ is compound → Cu replaces Ag → single displacement.

Check reactivity: Cu is above Ag? Yes → Cu can displace Ag.

Balance:
Left: Cu=1, Ag=2, S=1, O=4
Right: Ag=1, Cu=1, S=1, O=4 → need 2 Ag on right

So:
1 Cu + 1 Ag₂SO₄ → 2 Ag + 1 CuSO₄

Type: Single displacement

→ SINGLE

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10) ___ CuS + ___ KCl → ___ CuCl₂ + ___ K₂S

Two compounds → double displacement.

CuS and KCl → swap: Cu with Cl, K with S.

But check solubility? For worksheet, just balance.

Left: Cu=1, S=1, K=1, Cl=1
Right: Cu=1, Cl=2, K=2, S=1 → mismatch

Need 2 KCl on left → gives 2 K and 2 Cl
Then right: CuCl₂ (needs 2 Cl), K₂S (needs 2 K) → perfect.

So:
1 CuS + 2 KCl → 1 CuCl₂ + 1 K₂S

Type: Double displacement

→ DOUBLE

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Final Answers:

1) 1 Cl₂ + 2 KI → 2 KCl + 1 I₂ → SINGLE
2) 1 K₂CO₃ + 1 BaCl₂ → 2 KCl + 1 BaCO₃ → DOUBLE
3) 2 Na + 1 MgCl₂ → 2 NaCl + 1 Mg → SINGLE
4) 2 Al + 3 CuCl₂ → 2 AlCl₃ + 3 Cu → SINGLE
5) 2 Al + 3 Pb(NO₃)₂ → 2 Al(NO₃)₃ + 3 Pb → SINGLE
6) 2 AgNO₃ + 1 CaBr₂ → 2 AgBr + 1 Ca(NO₃)₂ → DOUBLE
7) 1 Al₂(SO₄)₃ + 1 Ca₃(PO₄)₂ → 2 AlPO₄ + 3 CaSO₄ → DOUBLE
8) 1 FeBr₂ + 1 K₂CO₃ → 1 FeCO₃ + 2 KBr → DOUBLE
9) 1 Cu + 1 Ag₂SO₄ → 2 Ag + 1 CuSO₄ → SINGLE
10) 1 CuS + 2 KCl → 1 CuCl₂ + 1 K₂S → DOUBLE

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Final Answer:
1) SINGLE
2) DOUBLE
3) SINGLE
4) SINGLE
5) SINGLE
6) DOUBLE
7) DOUBLE
8) DOUBLE
9) SINGLE
10) DOUBLE