Question

The amount of heat evolved when `500cm^(3)` of 0.1M HCl is mixed with `200cm^(3)` of 0.2 M NaOH is
A. 2.292 kJ
B. 1.292 kJ
C. 0.292 kJ
D. 3.392 kJ

Answer 1

Correct Answer - A
Mili-equivalent of HCl = `500xx0.1`
=50 milli-moles = 0.05 moles
Milli-equivalent of NaOH= `200xx0.2`
= 40 milli-moles = 0.04 moles
When 1 mole of `H^(+)` ions and 1 mole of `OH^(-)` ions are neutralized, 1 mole of water is formed and 57.1 kJ of energy is released.
0.04 moles of `H^(+)` ions react with 0.04 moles of `OH^(-)` ions to form 0.04 moles of water molecules. Heat evolved = `0.04xx57.1=2.29 kJ`.