1. 1)How many grams of solute are needed to saturate the given mass of H 2 O at the given temperature. A. at 40 o C 40 g KCl 100 g H 2 O B. at 10 0 C 80 g NaNO 3 = x x= 20 g 100 g H 2 O 25 g C. at 70 0 C 60 g NH 4 Cl = x x= 30 g 100 g H 2 O 50 g

2. 2)Is each solution saturated, unsaturated, or supersaturated? A. At 30 0 C 47 g KNO 3 have 50 g KNO 3 100 g H 2 O B. At 70 0 C 30 g Li 2 SO 4 = 3 g Li 2 SO 4 100 g H 2 O 10 g H 2 O C. At 50 0 C 37 g NaCl have 12 g = 24 g 100 g H 2 O 50 g 100g supersaturated saturated unsaturated

3. 3)Above what temperature must a solution of 10. g of copper (II) sulfate be heated to dissolve in 25 g water? 10 g CuSO 4 = 40 g CuSO 4 25 g H 2 O 100 g H 2 O So the solution must be 60 0 C or higher. The solubility at 60 0 C is 40 g CuSO 4 100 g H 2 O

4. 4) Why does SO 2 show a decrease in its solubility with an increase in temperature? The higher temperatures increase the molecular motion so the gas molecules escape more easily. The solubility of a gas in a liquid solvent decreases with increasing temperature. SO 2 is a gas at room temperature.

5. 5)A solution of KClO 3 contains 2 g dissolved in 20. g of water at 30 o C. How many more grams must be added to make a saturated solution at 70 o C? at 70 0 C 30 g KClO 3 = 6 g KClO 3 100 g H 2 O 20 g H 2 O Started with 2 g KClO 3 in 20 g of H 2 O. So you need to add 4 more grams of KClO 3 6 - 2 = 4