Some Basic Concepts of Chemistry - Result Question 52
####52. Liquid benzene $(C_6 H_6)$ burns in oxygen according to the equation
$2 C_6 H_6(l)+15 O_2(g) \longrightarrow 12 CO_2(g)+6 H_2 O(g)$
How many litres of $O_2$ at STP are needed to complete the combustion of $39 g$ of liquid benzene? (Mol. wt. of $O_2=32, C_6 H_6=78$ )
(a) $74 L$
(b) $11.2 L$
(c) $22.4 L$
(d) $84 L$
[1996]
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Solution:
- (d) $2 C_6 H_6+15 O_2(g) \longrightarrow 12 CO_2(g)+6 H_2 O(g)$ 2(78) 15(32)
$\because \quad 156 g$ of benzene, required oxygen $=15 \times 22.4$ litre
$\therefore 1 g$ of benzene, required oxygen $=\frac{15 \times 22.4}{156}$ litre
$\therefore \quad 39 g$ of benzene, required oxygen
$ =\frac{15 \times 22.4 \times 39}{156}=84.0 \text{ litre } $
