Question

Enthalpy of combustion of carbon to $CO _{2}$ is $-393.5 \,kJ \,mol ^{-1}$. What amount of heat will be released upon formation of $35.2 \,g$ of $CO _{2}$ from carbon and oxygen gas?

• A. 214.8 kJ
• B. 314.8 kJ
• C. 414.8 kJ
• D. 514.8 kJ

Answer 1

Answer: (B)

314.8 kJ

Answer 2

$\underset{12 \,g}{ C }+\underset{32\, g}{ O _{2}} \rightarrow \underset{44 \,g}{ CO _{2}} ; \Delta_{c} H=-393.5\, kJ \,mol ^{-1}$
$\because$ Due to $44\,g \,C O_{2}$,
heat releases $=393.5\, kJ$
$\therefore$ Due to $35.2 \,g \,CO _{2}$,
heat releases $=\frac{393.5 \times 35.2}{44}$
$=314.8\, kJ$