Q. The heat of combustion of carbon to $CO_{2}$ is $- 393$ kJ/mol. The heat released upon formation of 35.2 g of $CO_{2}$ from carbon and oxygen gas is
A) $+ 325\ kJ$
B) $- 31.5\ kJ$
C) $- 315\ kJ$
D) $+ 31.5\ kJ$
Explanation
(c)
$C + O_{2} \rightarrow CO_{2};\ \mathrm{\Delta}H = - 393.5$ kJ/mol
$\because\ \$44 g of $CO_{2}$ formed by which heat released $= - 393.5$ kJ
$\therefore\$1 g of $CO_{2}$ formed by which heat released $= \frac{- 393.5}{44}$
$\therefore\$35.2 g (given) of $CO_{2}$ formed by which heat released
$= - \frac{393.5}{44} \times 35.2 = - 314.8kJ$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.