Question

15.90 kJ and 18.58kJ are the heats absorbed when one mole of KCl is dissolved in 20 moles of water and 200 moles of waterrespectively. The heat of dilution of KCl is (in kJ)(A) -2.68(B) 2.68(C) 34.48(D) -34.48​

Answer 1

The change in enthalpy of hydration or dilution is 2.68 kJ.

Explanation:

The enthalpy of hydration or dilution is change in enthalpy when a solution containing 1 mole of solute is diluted from one concentration to other.

The change in enthalpy of hydration or dilution is given as:

ΔH enthalpy = 18.58 - 15.90

∴ ΔH enthalpy = 2.68 kJ

Answer 2

Explanation:

Given 15.90 kJ and 18.58 kJ are the heats absorbed when one mole of KCl is dissolved in 20 moles of water and 200 moles of water respectively. The heat of dilution of KCl is

• Given when one mole of KCL is dissolved in 20 moles of water the heat of dilution is 15.90 KJ
• Also when one mole of KCL is dissolved in 200 moles of water the heat of dilution is 18.58 KJ
• So the change in enthalpy when a solution has one mole of a solute is dissolved from one concentration to another is dilution.
• So the dilution is given by
• Δ dil h = Δh2 – Δh1
•          = 18.58 – 15.90
•        = -2.68 kJ