WAEC - Chemistry (2024 - No. 19)

Consider the reaction represented by the equation:

 C\(_3\)H\(_8\)  +  5 O\(_2\)  → 3CO\(_2\)  +  4H\(_2\)O

If 0.1 mole of C\(_3\)H\(_8\) was completely burnt, what volume of CO\(_2\) would be produced at stp? [volume of gas at stp = 22.4dm\(^3\)mol\(^{-1}\)].

6.72dm\(^3\)
2.24dm\(^3\)
0.30 dm\(^3\)
0.10dm\(^3\)

Explanation

 C\(_3\)H\(_8\)  +  5 O\(_2\)  → 3CO\(_2\)  +  4H\(_2\)O

From the equation: 1 mole :  3 moles

If  0.1 mole  reacted, then  0.3 mole will be formed.

⇒  0.3 mole of CO\(_2\) will be produced.

Recall that Number of moles of gases =  \(\frac{Volume}{Molar Volume of gas at stp}\)

 n =  \(\frac{V}{M.V}\)

 0.3 =  \(\frac{V}{22.4}\)

 V = 0.3 x 22.4

 V = 6.72 dm\(^3\)

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