Question

Heat of combustion of $C_2{H}_4$ is $-337KCal$. If $5.6lit{O}_2$ is used at STP, in the combustion heat liberated is ____ $K.Cal$.

• A. $28.08$
• B. $14.04$
• C. $42.06$
• D. $56.16$

Answer 1

The correct option is A $28.08$

Solution -

Combustion reaction -

$C_2{H}_4+O_2\to C{O}_2+H_{2}O$

After blancing the equation -

$C_2{H}_4+{30}_2\to 2C{O}_2+2H_{2}O$

At STP $22.4l$ $3\times 22.4l$ $2\times 22.4l$ $2\times 22.4l$

$22.4l$ $67.2l$ $44.8l$ $44.8l$

At $67.2l$ of $O_2$ the heat of

combustion = $-337kcal$

At $5.6l$ of $O_2$, the heat of

combustion = $\frac{337\times 5.6}{67.2}$

$\Rightarrow -28.08kcal$