1. Solutions Part I: The Solution Process

2. Solution:

3. Solutions: Solute: Solvent

4. Types of Solutions

5. The solution process To dissolve a solute in a solvent, the intermolecular attractions between solute and solute must be strong enough to compete with solvent- solvent and solute- solute attractions.

6. Solvation

7. Hydration

8. Dissolving an ionic solid in water The ion-dipole attractions between the salt and the solvent must be strong enough to overcome the lattice energy

9. “Steps” of the solution process Step 1

10. “Steps” of the solution process Step 1 Step 2

11. “Steps” of the solution process Step 1 Step 2 Step 3

12. Endothermic vs. exothermic?

13. Why do processes occur? Achieve a lower energy state Exothermic processes lead to lower enthalpy

14. Why do processes occur? More randomness Greater “entropy” Can more than compensate for increasing enthalpy

15. Did it dissolve, or did it react? Just because a substance “disappears” into a solvent doesn’t mean that the substance dissolved!

16. Dissolving vs. reaction Dissolving Physical change Can recover the original substance by evaporating the solvent

17. Dissolving vs. reaction Dissolving Physical change Can recover the original substance by evaporating the solvent Chemical change New substances form

18. Solutions saturated unsaturated

19. Supersaturated solutions

20. Will this substance dissolve?

21. “Like dissolves like” Non-polar substances tend to dissolve in non-polar solvents

22. “Like dissolves like” Non-polar substances tend to dissolve in non-polar solvents Polar substances tend to dissolve in polar solvents.

23. “Like dissolves like” It comes down to having similar intermolecular attractions.

24. Gases in solution Solubility depends on intermolecular attractions

25. Gases in solution Solubility depends on intermolecular attractions London forces As molar mass increases, dispersion forces are stronger

26. Henry’s Law The solubility of a gas in a liquid is directly dependent on the gas pressure

27. Henry’s Law The solubility of a gas in a liquid is directly dependent on the gas pressure Pressure really doesn’t affect solubility of solids and liquids

28. Henry’s Law S g = kP g

29. Solubility and temperature Usually, solubility of ionic solids increases with temperature

30. Gas solubility and temperature Solubility of gases typically decreases with increasing temperature