1. Lecture 7.5
Solution Energetics

2. I. Concentration

3. I. Concentration

4. I. Concentration
Ex #1: A solution is prepared by mixing 1.00 g ethanol (C2H5OH) with g water. The final volume is 101 mL. Calculate the density, mass percent, mole fraction, molarity, and molality of the solution.
1 g/mL, 0.99 %, , M, m

5. II. Solution Energies Three steps of formation of liquid solution:
Expanding the solute (+ΔH)
Expanding the solvent (+ΔH)
Interaction of solute and solvent (mixing, usually −ΔH)

6. II. Solution Energies
Enthalpy of solution
ΔHsoln = ΔH1 + ΔH2 + ΔH3

7. II. Solution Energies Alternatively:
Heat of hydration: enthalpy change of 1 mol gas solute ions dissolved in water.
ΔHhydration = ΔHsolvent + ΔHmix
ΔHsoln = ΔHsolute + ΔHhyd
endo exo
ΔHsolute = –ΔHlattice

8. II. Solution Energies

9. II. Solution Energies

10. II. Solution Energies

11. II. Solution Energies Ex #2:
Silver nitrate has a lattice energy of –820.0 kJ/mol and a heat of solution of kJ/mol. Calculate the heat of hydration for silver nitrate. Draw an energy diagram.
–797.4 kJ/mol

12. PS 7.5
Read section
Ch. 11: #25, all, all, all