Question

balancing equation quiz
balance the following equations and identify the type of reaction as
(s) synthesis, (d) decomposition, (sr) single replacement, (dr) double replacement, or
(c) combustion
type:
__ mg₃p₂ → mg + __ p
__ ch₄ + o₂ → co₂ + __ h₂o
__ naoh + h₂so₄ → na₂so₄ + __ h₂o

Explanation:

1. Balance first equation (decomposition)

Step1: Balance Mg atoms

$1\text{Mg}_3\text{P}_2
ightarrow 3\text{Mg} + \text{P}$

Step2: Balance P atoms

$1\text{Mg}_3\text{P}_2
ightarrow 3\text{Mg} + 2\text{P}$

Step3: Identify reaction type

A single compound breaks into simpler substances, so it is decomposition.

2. Balance second equation (combustion)

Step1: Balance C atoms

$1\text{CH}_4 + \text{O}_2
ightarrow 1\text{CO}_2 + \text{H}_2\text{O}$

Step2: Balance H atoms

$1\text{CH}_4 + \text{O}_2
ightarrow 1\text{CO}_2 + 2\text{H}_2\text{O}$

Step3: Balance O atoms

$1\text{CH}_4 + 2\text{O}_2
ightarrow 1\text{CO}_2 + 2\text{H}_2\text{O}$

Step4: Identify reaction type

A hydrocarbon reacts with $\text{O}_2$ to produce $\text{CO}_2$ and $\text{H}_2\text{O}$, so it is combustion.

3. Balance third equation (double replacement)

Step1: Balance Na atoms

$2\text{NaOH} + \text{H}_2\text{SO}_4
ightarrow 1\text{Na}_2\text{SO}_4 + \text{H}_2\text{O}$

Step2: Balance H and O atoms

$2\text{NaOH} + 1\text{H}_2\text{SO}_4
ightarrow 1\text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}$

Step3: Identify reaction type

Ions swap between two compounds, so it is double replacement.

Answer:

1. $\boldsymbol{1\text{Mg}_3\text{P}_2

ightarrow 3\text{Mg} + 2\text{P}}$
Type: (D) Decomposition

1. $\boldsymbol{1\text{CH}_4 + 2\text{O}_2

ightarrow 1\text{CO}_2 + 2\text{H}_2\text{O}}$
Type: (C) Combustion

1. $\boldsymbol{2\text{NaOH} + 1\text{H}_2\text{SO}_4

ightarrow 1\text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}}$
Type: (DR) Double Replacement