Chemistry - Thermochemistry Question with Solution | TestHub

Question Explanation: Find the temperature increase in a neutralization reaction.

Concept: Enthalpy of Neutralization.

Solution:

Heat released during neutralization ( $\mathrm{Q}=\mathrm{n}\times \Delta \mathrm{H}$ ) increases the solution temperature according to $\mathrm{Q}=\mathrm{mc}\Delta \mathrm{T}$.

${\mathrm{H}}_{(\mathrm{aq})}^{+}+{\mathrm{OH}}_{(\mathrm{aq})}^{-}\to {\mathrm{H}}_2\mathrm{O}(\ell )\Delta \mathrm{H}=-13.7\frac{\mathrm{Kcal}}{\mathrm{eq}}$

$$\text{ no. of }\begin{array}{rlr}{\mathrm{m}}_{\mathrm{eq}}\text{ of }{\mathrm{OH}}^{-}& =224\times 0.1\times 1& =22.4\end{array}$$

no. of ${\mathrm{m}}_{\text{eq }}$ of ${\mathrm{H}}^{+}=50\times 0.1\times 2$

$$=10\text{ (Limiting reagent) }$$

A neutralisation $10{\mathrm{m}}_{\mathrm{eq}}$ of acid will occur

Heat released $=13.7\times 0.01\times 1000\mathrm{cal}.=137\mathrm{cal}$.

$\because \mathrm{q}=\mathrm{mS}\Delta \mathrm{T}$

$137=(224+50)\times 1\times \Delta \mathrm{T}$

$\therefore \Delta \mathrm{T}=0.5\mathrm{K}$

Final Answer: 0.5 K