Types of Chemical Reactions Worksheets - Free Printable - Free Printable

Absolutely! Let’s solve both sections of this worksheet step by step, predicting the products and balancing each chemical equation. I’ll explain the reasoning behind each reaction type and product formation.

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## SECTION A: Predict Products & Balance Equations

1) C: C₃H₆O + O₂ → ?

Type: Combustion (C)
Combustion of organic compounds (especially hydrocarbons or oxygen-containing organics) with O₂ produces CO₂ and H₂O.

Unbalanced:
C₃H₆O + O₂ → CO₂ + H₂O

Balance:
- Carbon: 3 on left → 3CO₂
- Hydrogen: 6H on left → 3H₂O
- Oxygen: Left has 1 (from C₃H₆O) + 2x (from O₂); Right has 6 (from 3CO₂) + 3 (from 3H₂O) = 9 O atoms.
→ So we need 8 more O atoms from O₂ → 4 O₂ molecules.

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

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2) DR: CuCl₂ + H₂S → ?

Type: Double Replacement (DR)
General form: AB + CD → AD + CB
Here: Cu²⁺ pairs with S²⁻ → CuS (insoluble precipitate)
H⁺ pairs with Cl⁻ → HCl (aqueous)

Unbalanced:
CuCl₂ + H₂S → CuS + HCl

Balance:
- 2 Cl on left → 2 HCl on right
- 2 H on left → matches 2 H in 2HCl

✔ Balanced Equation:
CuCl₂ + H₂S → CuS↓ + 2HCl

*(Note: CuS is a black precipitate — often indicated with ↓)*

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3) D: ZnCO₃ → ?

Type: Decomposition (D)
Metal carbonates decompose to metal oxide + CO₂ when heated.

ZnCO₃ → ZnO + CO₂

Already balanced!

✔ Balanced Equation:
ZnCO₃ → ZnO + CO₂

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4) SR: Na + MgCl₂ → ?

Type: Single Replacement (SR)
More reactive metal (Na) replaces less reactive metal (Mg) in compound.

Check reactivity series: Na > Mg → so yes, reaction occurs.

Na replaces Mg:
Na + MgCl₂ → NaCl + Mg

Balance:
- 2 Na needed to balance 2 Cl → 2NaCl
- Mg is already balanced

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

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5) S: K + Cl₂ → ?

Type: Synthesis (S)
Two elements combine to form a compound.

K (metal) + Cl₂ (nonmetal) → KCl (ionic compound)

Balance:
- 2K needed to react with Cl₂ → 2KCl

✔ Balanced Equation:
2K + Cl₂ → 2KCl

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6) SR: Cu + AgNO₃ → ?

Type: Single Replacement (SR)
Cu replaces Ag if Cu is more reactive. Check activity series: Cu > Ag? Actually, NO — Cu is LESS reactive than Ag? Wait — correction!

✔ Correction: Ag is BELOW Cu in the activity series, meaning Cu IS MORE REACTIVE than Ag → so reaction DOES occur.

Cu + AgNO₃ → Cu(NO₃)₂ + Ag

Balance:
- 2 AgNO₃ needed for 2 Ag atoms
- Cu(NO₃)₂ has 2 NO₃⁻ → matches 2 AgNO₃

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

*(Silver metal precipitates — shiny coating)*

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7) D: NO₂ → ?

Type: Decomposition (D)
NO₂ can decompose, especially under heat or light, into NO and O₂.

2NO₂ → 2NO + O₂

Check balance:
- N: 2 = 2
- O: 4 = 2 (in 2NO) + 2 (in O₂) = 4 ✓

✔ Balanced Equation:
2NO₂ → 2NO + O₂

*(This is a common decomposition in smog chemistry)*

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8) DR: CaO + Mg(NO₃)₂ → ?

Type: Double Replacement (DR)
CaO is a base; Mg(NO₃)₂ is a salt. But CaO is not soluble — it reacts with water first? However, in dry conditions or as written, double replacement may not proceed easily.

Actually, CaO + Mg(NO₃)₂ → no reaction? But let’s think chemically.

Double replacement would give: Ca(NO₃)₂ + MgO

Both are solids or slightly soluble — but MgO is insoluble, Ca(NO₃)₂ is soluble. So possibly:

CaO + Mg(NO₃)₂ → Ca(NO₃)₂ + MgO

But this is not typical unless in aqueous solution — and CaO reacts with water to form Ca(OH)₂.

However, if we assume direct reaction, then:

Unbalanced:
CaO + Mg(NO₃)₂ → Ca(NO₃)₂ + MgO

Already balanced!

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

*(Note: This reaction is not very favorable thermodynamically, but for worksheet purposes, this is acceptable.)*

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## SECTION B: Write Equations & Balance Them

1) SR: Magnesium bromide + Chlorine → ?

Type: Single Replacement
Cl₂ will replace Br⁻ if Cl is more reactive → YES (Cl > Br in halogen reactivity).

MgBr₂ + Cl₂ → MgCl₂ + Br₂

Balance:
- 2 Br on left → Br₂ on right
- Already balanced for Mg and Cl

✔ Balanced Equation:
MgBr₂ + Cl₂ → MgCl₂ + Br₂

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2) DR: Silver nitrate + Zinc chloride → ?

Type: Double Replacement
AgNO₃ + ZnCl₂ → AgCl + Zn(NO₃)₂

AgCl is insoluble (precipitate), Zn(NO₃)₂ is soluble.

Balance:
- 2 AgNO₃ needed to provide 2 NO₃⁻ for Zn(NO₃)₂
- 2 AgCl formed

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

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3) S: Aluminum + Oxygen → ?

Type: Synthesis
Aluminum metal reacts with oxygen to form aluminum oxide.

Al + O₂ → Al₂O₃

Balance:
- 4Al + 3O₂ → 2Al₂O₃

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

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4) D: Magnesium hydroxide → ?

Type: Decomposition
Metal hydroxides decompose to metal oxide + water when heated.

Mg(OH)₂ → MgO + H₂O

Already balanced!

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

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5) S: Magnesium + Iodine → ?

Type: Synthesis
Metal + nonmetal → ionic compound.

Mg + I₂ → MgI₂

Balance:
- Mg + I₂ → MgI₂ (already balanced)

✔ Balanced Equation:
Mg + I₂ → MgI₂

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6) SR: Sodium + Water → ?

Type: Single Replacement
Very reactive metal + water → metal hydroxide + hydrogen gas.

Na + H₂O → NaOH + H₂

Balance:
- 2Na + 2H₂O → 2NaOH + H₂

✔ Balanced Equation:
2Na + 2H₂O → 2NaOH + H₂↑

*(Vigorous reaction — hydrogen gas evolved)*

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## ✔ FINAL ANSWERS SUMMARY:

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SECTION 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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SECTION 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 why certain reactions occur (e.g., activity series, solubility rules, etc.) — happy to dive deeper!