Question

The heat evolved when 0.25 mole of hydrochloric acid in solution is neutralized by 0.25 mole of Sodium hydroxide solution is :

• A. 57.1 kJ
• B. 14.3 kJ
• C. 28.55 kJ
• D. None

Answer 1

The correct option is B 14.3 kJ

The reaction between HCl and NaOH in solution is :
$HCl\left(aq\right)+NaOH\left(aq\right)\to NaCl\left(aq\right)+H_{2}O\left(l\right)H^{+}\left(aq\right)+O{H}^{-}\left(aq\right)\to H_{2}O\left(l\right)0.25mol$
Both the acid and base are strong and their basicity as well acidity are equal to 1. This means that their grams molar masses are the same as the gram equivalent masses.
1 mole of HCl when neutralized by 1 mole of NaOH, heat evolved = 57.1 kJ
0.25 mole of HCl when neutralized by 0.25 mole of NaOH evolve heat = 57.1 $\times$ 0.25 = 14.3 kJ