1. Tardigrade
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  3. Chemistry
  4. 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:

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Q. 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:

Thermodynamics

Solution:

$C _{6} H _{5} COOH ( s )+\frac{15}{2} O _{2}( g )$ $\rightarrow 7 CO _{2}( g )+3 H _{2} O (l)$

$\Delta n _{ g }=7-\frac{15}{2}=\frac{-1}{2}$

$\Delta H =\Delta E +\Delta n _{ g } RT$

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