Question

$150mL$ of $0.5N$ nitric acid solution at $25.35^{\circ }C$ was mixed with $150mL$ of $0.5N$ sodium hydroxide solution at the same temperature. The final temperature was recorded to be $28.77^{\circ }C$. Heat of neutralisation of nitric acid with sodium hydroxide

• A. -12.64 kcal
• B. -11.98 kcal
• C. -13.68 kcal
• D. -12.68 kcal

Answer 1

Answer: (C)

Total mass of solution $=150+150$
$=300g$
$Q=$ Total heat produced $=300\times (28.77-25.35)$ cal
$=300\times 3.42=1026cal$
Heat of neutralisation $=\frac{Q}{150}\times 1000\times \frac{1}{0.5}$ $=\frac{1026}{150}\times 1000\times \frac{1}{0.5}$
$=13.68kcal$
Since, heat is liberated, heat of neutralisation should be negative.
Hence, $\Delta H_{\text{neut }}=-13.68kcal$.