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WAEC Chemistry 2024 Paper

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Question : 19

Total: 50

Consider the reaction represented by the equation:

6.72dm $^{3}$
2.24dm $^{3}$
0.30 dm $^{3}$
0.10dm $^{3}$

Solution:

Concept:

Use the mole ratio from the balanced equation and molar gas volume at STP to find the volume of

\mathrm{CO_2}

produced.

Explanation:

The balanced equation is:

\mathrm{C_3H_8} + 5\mathrm{O_2} \rightarrow 3\mathrm{CO_2} + 4\mathrm{H_2O}

From the equation,

1

mole of

\mathrm{C_3H_8}

gives

3

moles of

\mathrm{CO_2}

.

So,

0.1

mole of

\mathrm{C_3H_8}

gives:

0.1 \times 3 = 0.3 \text{ moles of } \mathrm{CO_2}

At STP,

1

mole of gas occupies

22.4 \text{ dm}^3

.

Volume of

\mathrm{CO_2}

produced:

V = n \times 22.4

V = 0.3 \times 22.4 = 6.72 \text{ dm}^3

Answer:

The volume of

\mathrm{CO_2}

produced is

6.72 \text{ dm}^3

.

Correct option: A.

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