Question

For the reaction –

CO (g) + $\frac{1}{2}$O₂ (g) ¾® CO₂ (g) ;

DH° = – 67650 cal at 25⁰ C.

Calculate DH⁰ at 100⁰C, given that the required molar heat capacities are as follows –

C_P (CO, gas) = 6.97 cal/°C

C_P (CO₂, gas) = 8.47 cal/°C

C_P (O₂­, gas) = 7.00 cal/°C

• A. –54.6 cal
• B. –67650.4 cal
• C. –67684.4 cal
• D. –67762.5 cal

Answer 1

Answer: (D)

–67762.5 cal

Answer 2

$\Delta H_{100}^{{^\circ}}–\Delta H_{25{^\circ}C}^{{^\circ}}$ = $\left( C_{P_{2}}–C_{P_{1}} \right)$ DT

̃ $\Delta H_{100}^{{^\circ}}$ = 75 (8.97 – 6.97 – $\frac{7}{2}$) + $\Delta H_{25{^\circ}C}^{{^\circ}}$

= (–112.50 – 67650) cal

= – 67762.5 cal