A certain ionic compound has a ΔH soln = -65.4 kJ/mol. Which of the following conclusions...

A certain ionic compound has a ΔH soln = -65.4 kJ/mol. Which of the following conclusions is correct? A certain ionic compound has a ΔH soln = -65.4 kJ/mol. Which of the following conclusions is correct?

ΔH solute ≈ 0,

ΔH hydration < 0

ΔH solute < ΔH hydration

ΔH solute ≈ ΔH hydration

ΔH solute > ΔH hydration

Expert Solution

Heat absorbed or released when a specified amount of a solute dissolves in a certain quantity of solvent at constant pressure is known as enthalphy of solution (H_solution)

ΔH soln = -65.4 kJ/mol, Here negative shows that heat is released in the process.

Dissolving of ionic compound in water takes place in two steps:

1. Breaking of ionic bonds between ions, this steps involves absorption of heat i.e., endothermic process - Lattice enthalphy

2.Hydration of ions formed (ion dipole of interactions between ions and water molecules). It is a exothermic steps i.e., heat is released- Enthaphy of hydration

Enthalphy of solution will be negative or positive will depends on both the factors discussed.

If the enthalphy of hydration is greater than the lattice enthalpy, it means more heat is released than absorbed. Then enthalphy of solution will be negative.

If the enthalphy of hydration is less than the lattice enthalphy, it means heat released is less than heat absorbed. Then enthalphy of solution will be positive.

We can conclude that in the given case ΔH solute < ΔH hydration

queen_honey_blossom answered 2 years ago

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