Question

Equal volumes of $1M$ $HCl$ and $1M$ $H_{2}S{O}_4$ are neutralized by dilute NaOH solution liberating $x$ kcal and $y$ kcal heat. Which of the following is correct?

• A. $x=y$
• B. $x=0.5y$
• C. $x=0.4y$
• D. None of these

Answer 1

The correct option is B $x=0.5y$

Reaction involved are:

$HCl+NaOH\to NaCl+H_{2}O,\Delta H_1=xkcal$

$H_{2}S{O}_4+2NaOH\to N{a}_{2}S{O}_4+2H_{2}O,\Delta H_1=ykcal$

(i) acid-base neutralization reaction for HCl is represented as:

$H^{+}+O{H}^{-}\to H_{2}O,\Delta H_1=xkcal$

(ii) acid-base neutralization reaction for $H_{2}S{O}_4$ is represented as:

$2H^{+}+2O{H}^{-}\to 2H_{2}O,\Delta H_1=ykcal$

since reaction (ii) is twice of reaction (i), so is the enthalpies

thus $2x=y$

or $x=0.5y$