Question

One gram sample of ammonium nitrate is decomposed in a bomb calorimeter. The temperature of calorimeter increases by $6.12K$. The heat capacity of the system is $1.23kJ/g/deg$. What is the molar heat of decomposition of ${NH}_4{NO}_3$?

• A. $-7.53kJ{mol}^{-1}$
• B. $-398.1kJ{mol}^{-1}$
• C. $-16.1kJ{mol}^{-1}$
• D. $-602kJ{mol}^{-1}$

Answer 1

The correct option is C $-16.1kJ{mol}^{-1}$

Heat capacity $Q=nC\Delta T=\frac{w}{M}C\Delta T$
or $1.23=\frac{1}{80}\times C\times 6.12$
$C=16.1kJ{mol}^{-1}$
As heat releases in this reaction, hence it is an exothermic reaction. Therefore molar heat of decomposition of ${NH}_4{NO}_3$ will be $-16.1kJ{mol}^{-1}$