Enthalpy of solution and hydration

Question 1

What is the enthalpy of solution

Answer 1

ΔHsolꝋ when 1 mole of an ionic substance dissolves in sufficient water to form an infinitely dilute solution

KCl(s) + aq → KCl(aq)
OR
KCl(s) + aq → K+(aq) + Cl-(aq)

Question 2

What is the enthalpy of hydration?

Answer 2

ΔHhydꝋ is when 1 mole of a gaseous ion dissolves in sufficient water to form an infinitely dilute solution

The energy released when bonds form between ions and water molecules, so it is exothermic.

Question 3

What equation is used to calculate enthalpy of hydration involving lattice enthalpy?

Answer 3

ΔHsolꝋ = ΔHlattꝋ + ΔHhydꝋ

Question 4

Calculation for MgCl2

Answer 4