Question

What is the heat of reaction for the above reaction given the heat of formation, $\Delta H_f$ of ${NO}_2\left(g\right)$ is $34kJ/mole$ and $N_2{O}_4\left(g\right)$ is $10kJ/mole$?

• A. $-58kJ$
• B. $-48kJ$
• C. $10kJ$
• D. $48kJ$
• E. $78kJ$

Answer 1

Answer: (A)

$-58kJ$

$2NO2$ $\to$ $N2O4$

Given,

$\Delta Hf$ of $NO2$ = $34kJ/mol$

$\Delta Hf$ of $N2O4$ = $10kJ/mol$

Therefore

Heat of Reaction = $10-(2\times 34)kJ$

= $-58kJ$