Question

$28.0\, L$ of $CO _2$ is produced on complete combustion of $168 \, L$ gaseous mixture of ethene and methane at $25^{\circ} C$ and $1 \, atm$ Heat evolved during the combustion process is ______$kJ$ Given : $\Delta H _{ c }\left( CH _4\right)=-900 \, kJ\, mol ^{-1}$ $\Delta H _{ c }\left( C _2 H _4\right)=-1400\, kJ \, mol ^{-1}$

Answer 1

Correct Answer: 925

The correct answer is 925.

$\Rightarrow 28=16.8+x$
$x=11.2L$
$n_{C{H}_4}=\frac{PV}{RT}=\frac{1\times 5.6}{0.082\times 298}=0.229\text{mole}$
$n_{C_2{H}_2}=\frac{11.2}{0.082\times 298}=0.458\text{mole}$
$\therefore \text{Heat evolved}=0.229\times 900+0.458\times 1400$
$=206.1+641.2$
$=847.3kJ$