Question

Heat of combustion of $C{H}_{4\left(g\right)}$ at constant volume is measured in bomb calorie-meter at $298.2$K and found to be $885389$ find the valve of enthalpy.
$N_{2\left(g\right)}+3H_{2\left(g\right)}\to 2N{H}_{3\left(g\right)}$.

Answer 1

Enthalpy can be determined by $\Delta H=\Delta U+\Delta n_{g}RT$

Combustion of methane:-

$\underset{\left(g\right)}{C{H}_4}+\underset{\left(g\right)}{2O_2}⟶\underset{\left(g\right)}{C{O}_2}+\underset{\left(l\right)}{2H_{2}O}$

$\Rightarrow \Delta n_g=1-3=(-2)$

$\Delta H=\Delta U-2RT$

Given, Heat of combustion= $885389kJ/mol$

$\Rightarrow \Delta H=885389-\frac{2\left(8.314\right)\left(298\right)}{1000}$

$=(885389-4.95)kJ/mol$

$\therefore$ Enthalpy is= $885384.05kJ/mol$