Question

The heat of neutralization for 2 moles of LiOH and
1 mole of H2SO4, at 25°C is -69.6 KJ. The heat of
ionisation of LiOH will be nearly :-
(1) 22.5 KJ mol-'
(2) 90 KJ mol-1
(3) 45 KJ mol-1
(4) 33.6. KJ mol-1​

Answer 1

Given:

• Number of moles of LiOH = 2
• Number of moles of H₂SO₄ = 1
• Heat of neutralization (Hn) = -69.6 KJ

To find:

The heat of ionization of LiOH (Hi).

Solution:

• The amount of heat released when one mole of H⁺ from strong acid reacts with one mole of OH⁻ from strong base (Hr) is approximately equal to -57 KJ/mol.
• Here, two moles of acid and base are getting neutralized and some of the heat produced is used up in ionizing LiOH. Hence, Hn = 2Hr + 2Hi
• Therefore, Hi = (Hn-2Hr)/2 ≅ 22.5 KJ/mol.

Answer:

The heat of ionization of LiOH (Hi) ≅ 22.5 KJ/mol