1. Factors Affecting Solubility

2. Molecular Structure “Like dissolves like” Polar substances dissolve well in polar solvents Non-polar substances dissolve well in non- polar solvents Has to do with the heats absorbed or released in the dissolving process

3.  H 1  H 2  H 3  H soln Outcome ------------------------------------------------------------- Polar Solute, Polar Solvent Polar Solute, Non-Polar solv Non-polar solute, Non-Polar solv Non-polar solute, Polar Solvent

4. Pressure Has little or no effect on the solubilities of liquids or solids Has a great effect on the solubility of gases Higher the pressure, the greater the solubility of a gas

5. Henry’s Law The amount of gas dissolved in a solution is directly proportional to the pressure of the gas above the solution P = kC P- partial pressure of the gas k – constant of the solution C – concentration of the solution

6. Example A soft drink is bottled so that a bottle at 25°C contains carbon dioxide gas at a pressure of 5.0atm over the liquid. The Henry’s law constant for carbon dioxide in solution is 32 L atm/mol. Calculate the concentration of carbon dioxide in the soda.

7. Temperature For most solids and liquids, solubility increases with increasing temperature For some though, solubility decreases as temp increases There is no way to really predict how solubility of liquids and solids will change with temp. Experimental results are the only thing reliable

8. Example From solubility graph on page 525, tell solubility of a) sugar at 50°C b) cerium sulfate at 20°C c) potassium nitrate at 80°C

9. Temp and Gases Solubility of gases decreases with increasing temperature What is thermal pollution?