Question

$28.0L$ of $C{O}_2$ is produced on complete combustion of $16.8L$ gaseous mixture of ethene and methane at $25^{\circ }C$ and $1atm$. Heat evolved during the combustion process is ______$kJ$.
Given : $\Delta H_c\left(C{H}_4\right)=-900kJmo{l}^{-1}$
$\Delta H_c\left(C_2{H}_4\right)=-1400kJmo{l}^{-1}$

Answer 1

Answer: 925

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