Question

The enthalpy of a certain reaction at $273K$ is $-20.75kJ$.The enthalpy of same reaction at $373K$ (if heat capacities of reactants and products is same) will be:

• A. $-2075kJ$
• B. $2075kJ$
• C. Zero
• D. $-20.75\times \frac{337}{273}kJ$

Answer 1

Answer: (A)

$-2075kJ$

From Kirchoff's equation
$\frac{\Delta H_2-\Delta H_1}{T_2-T_1}=\Delta C_p$
As both have same heat capacities, $\Delta C_p=0$
or $\Delta H_2=\Delta H_1\therefore \Delta H_2=-20.75kJ$