Types of Chemical Reactions Worksheets - Free Printable - Free Printable

Let's solve each part of this chemistry worksheet step by step, predicting the products and balancing the chemical equations.

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Part A: Predict Products and Balance Equations

#### 1) C: C₃H₆O + O₂ →
This is a combustion (C) reaction. Hydrocarbons or organic compounds with oxygen combust to form CO₂ and H₂O.

Unbalanced:
C₃H₆O + O₂ → CO₂ + H₂O

Now balance:

- Carbon: 3 on left → 3 CO₂
- Hydrogen: 6 on left → 3 H₂O (since each H₂O has 2 H)
- Oxygen: Left side = 1 (from C₃H₆O) + 2×O₂ = ?
Right side: 3×2 = 6 from CO₂ + 3×1 = 3 from H₂O → total 9 O atoms

So we need 8 more O atoms from O₂ → 4 O₂ molecules.

Check:
- C₃H₆O + 4O₂ → 3CO₂ + 3H₂O

But let’s count:
- Left: C=3, H=6, O=1 + 8 = 9
- Right: C=3, H=6, O=6+3=9 ✔

✔ Balanced equation:
C₃H₆O + 4O₂ → 3CO₂ + 3H₂O

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#### 2) DR: CuCl₂ + H₂S →
Double replacement: ions swap partners.

Cu²⁺ pairs with S²⁻ → CuS
H⁺ pairs with Cl⁻ → HCl

Unbalanced:
CuCl₂ + H₂S → CuS + 2HCl

Balance:
- Already balanced: 1 Cu, 2 Cl, 2 H, 1 S on both sides.

✔ Balanced equation:
CuCl₂ + H₂S → CuS + 2HCl

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#### 3) D: ZnCO₃ →
Decomposition: carbonate breaks down into metal oxide and CO₂.

ZnCO₃ → ZnO + CO₂

✔ Already balanced.

✔ Balanced equation:
ZnCO₃ → ZnO + CO₂

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#### 4) SR: Na + MgCl₂ →
Single replacement: Na is more reactive than Mg (Na higher in activity series), so it replaces Mg.

Na + MgCl₂ → NaCl + Mg

But need to balance:
- Na: 1 on left, 1 on right → OK
- Mg: 1 → 1 → OK
- Cl: 2 on left → need 2 NaCl

So:
2Na + MgCl₂ → 2NaCl + Mg

✔ Balanced equation:
2Na + MgCl₂ → 2NaCl + Mg

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#### 5) S: K + Cl₂ →
Synthesis: metal + nonmetal → ionic compound.

K is +1, Cl is -1 → KCl

2K + Cl₂ → 2KCl

✔ Balanced equation:
2K + Cl₂ → 2KCl

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#### 6) SR: Cu + AgNO₃ →
Single replacement: Check activity series — Cu is *less* active than Ag? Wait: Ag is less active than Cu, so Cu can replace Ag.

Yes! Copper is above silver in the activity series.

So:
Cu + AgNO₃ → Cu(NO₃)₂ + Ag

Now balance:
- Cu: 1 → 1
- Ag: 1 → 1 → but AgNO₃ has one Ag, Cu(NO₃)₂ has two NO₃⁻ → need 2 AgNO₃

So:
Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag

✔ Balanced equation:
Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag

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#### 7) D: NO₂ →
Decomposition: Nitrogen dioxide decomposes?

Actually, NO₂ is stable under normal conditions, but if heated, it may decompose to NO and O₂.

But common decomposition for nitrogen oxides:
2NO₂ → 2NO + O₂

✔ Balanced equation:
2NO₂ → 2NO + O₂

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#### 8) DR: CaO + Mg(NO₃)₂ →
Double replacement: Ca²⁺ swaps with Mg²⁺

CaO is not soluble, but it can react in water, but here we assume it reacts as ions.

CaO + Mg(NO₃)₂ → Ca(NO₃)₂ + MgO

But check solubility:
- Ca(NO₃)₂ is soluble
- MgO is insoluble (basic oxide)

So possible precipitation of MgO.

But CaO is also a base. This might be an acid-base-like reaction, but no H⁺ present.

Alternatively, consider that CaO reacts with water first, but since no water is shown, perhaps just ion exchange.

But both CaO and MgO are solids. So maybe no reaction? But assuming they react:

CaO + Mg(NO₃)₂ → Ca(NO₃)₂ + MgO

Now balance:
- All elements: 1 Ca, 1 Mg, 2 NO₃, 1 O from CaO, 1 O from MgO → wait, O atoms: left: 1 (from CaO) + 6 (from 2 NO₃) = 7; right: 6 (NO₃) + 1 (MgO) = 7 → OK

But better to write clearly:

CaO + Mg(NO₃)₂ → Ca(NO₃)₂ + MgO

✔ Balanced.

✔ Balanced equation:
CaO + Mg(NO₃)₂ → Ca(NO₃)₂ + MgO

(Note: This may not proceed readily unless in aqueous solution, but based on double replacement logic, this is acceptable.)

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Part B: Predict Products and Balance

#### 1) SR: Magnesium bromide + Chlorine →
Magnesium bromide: MgBr₂
Chlorine: Cl₂

Single replacement: Cl₂ is more reactive than Br₂, so Cl replaces Br.

MgBr₂ + Cl₂ → MgCl₂ + Br₂

Balance:
- Mg: 1 → 1
- Br: 2 → 2 → so Br₂
- Cl: 2 → 2 → Cl₂

✔ Balanced equation:
MgBr₂ + Cl₂ → MgCl₂ + Br₂

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#### 2) DR: Silver nitrate + Zinc chloride →
AgNO₃ + ZnCl₂ → ?

Swap ions: Ag⁺ with Cl⁻ → AgCl (insoluble!)
Zn²⁺ with NO₃⁻ → Zn(NO₃)₂ (soluble)

So precipitate of AgCl forms.

AgNO₃ + ZnCl₂ → AgCl + Zn(NO₃)₂

Balance:
- Ag: 1 → 1 → need 2 AgNO₃ for 2 AgCl
- Cl: 2 → 2 → need 2 AgCl
- Zn: 1 → 1
- NO₃: 2 → 2 → need 2 AgNO₃

So:
2AgNO₃ + ZnCl₂ → 2AgCl + Zn(NO₃)₂

✔ Balanced equation:
2AgNO₃ + ZnCl₂ → 2AgCl + Zn(NO₃)₂

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#### 3) S: Aluminum + Oxygen →
Aluminum oxidizes to Al₂O₃

4Al + 3O₂ → 2Al₂O₃

✔ Balanced equation:
4Al + 3O₂ → 2Al₂O₃

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#### 4) D: Magnesium hydroxide →
Decomposition: Metal hydroxides decompose to metal oxide and water.

Mg(OH)₂ → MgO + H₂O

✔ Already balanced.

✔ Balanced equation:
Mg(OH)₂ → MgO + H₂O

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#### 5) S: Magnesium + Iodine →
Synthesis: Mg + I₂ → MgI₂

Balance:
- Mg: 1 → 1
- I: 2 → 2

✔ Balanced equation:
Mg + I₂ → MgI₂

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#### 6) SR: Sodium + Water →
Sodium reacts violently with water:
2Na + 2H₂O → 2NaOH + H₂

Note: Not Na + H₂O → NaOH + H₂ (unbalanced)

Balance:
- Na: 2 → 2
- H: 4 from 2H₂O → 2 in 2NaOH and 2 in H₂ → total 4 H
- O: 2 → 2

✔ Balanced equation:
2Na + 2H₂O → 2NaOH + H₂

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✔ Final Answers Summary:

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Part A:

1) C₃H₆O + 4O₂ → 3CO₂ + 3H₂O
2) CuCl₂ + H₂S → CuS + 2HCl
3) ZnCO₃ → ZnO + CO₂
4) 2Na + MgCl₂ → 2NaCl + Mg
5) 2K + Cl₂ → 2KCl
6) Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag
7) 2NO₂ → 2NO + O₂
8) CaO + Mg(NO₃)₂ → Ca(NO₃)₂ + MgO

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Part B:

1) MgBr₂ + Cl₂ → MgCl₂ + Br₂
2) 2AgNO₃ + ZnCl₂ → 2AgCl + Zn(NO₃)₂
3) 4Al + 3O₂ → 2Al₂O₃
4) Mg(OH)₂ → MgO + H₂O
5) Mg + I₂ → MgI₂
6) 2Na + 2H₂O → 2NaOH + H₂

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Let me know if you'd like explanations for any specific reaction!