The heat of combustion of solid benzoic' acid at constant volume is -321.30 kJ at 27° C . The heat of combustion at constant pressure is:

Question

The heat of combustion of solid benzoic' acid at constant volume is -321.30 kJ at 27° 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

Tardigrade Admin · Accepted Answer

C 6 H 5 COOH ( s )+(15/2) O 2( g ) arrow 7 CO 2( g )+3 H 2 O (l) Δ n g =7-(15/2)=(-1/2) Δ H =Δ E +Δ n g RT =-321.30+((-1/2)) R × 300

Q. The heat of combustion of solid benzoic' acid at constant volume is $- 321.30 k J$ at $2 7^{\circ} C .$ The heat of combustion at constant pressure is:

-321.30-300 R

-321.30+300 R

-321.30-150 R

-321.30+900 R

$C_{6} H_{5} COO H (s) + \frac{15}{2} O_{2} (g)$ $\to 7 C O_{2} (g) + 3 H_{2} O (l)$

$Δ n_{g} = 7 - \frac{15}{2} = \frac{- 1}{2}$

$Δ H = Δ E + Δ n_{g} RT$

$= - 321.30 + (\frac{- 1}{2}) R \times 300$

Q. The heat of combustion of solid benzoic' acid at constant volume is −321.30kJ at 27∘C. The heat of combustion at constant pressure is: