Browse Questions

At constant volume the heat of combustion of solid benzoic acid at constant volume is -321.30 kJ at $27^\circ C$. The heat of combustion at constant pressure is

(a) -321.30 - 300 R
(b) -321.30 + 300 R
(c) -321.30 - 150 R
(d) -321.30 + 900 R

$C_6H_5COOH (s) + \frac{15}{2} O_2(g) \longrightarrow 7CO_2(g) + 3H_2O(l)$
Since, $\Delta n_g = n_P - n_R$
$\Delta n_g$ = 7 - $\frac{15}{2} = \frac{-1}{2}$
$\Delta H = \Delta E + \Delta n_g RT$
$\Delta H = -321.30 - ( \frac{1}{2} \times R \times 300 )= -321.30 - 150 R$