1. Solutions

2. Solution Saturation Compares the amount of dissolved solute in a solution with the maximum amount of dissolved solute possible under the given conditions.

3. Solubility SATURATED SOLUTION no more solute dissolves UNSATURATED SOLUTION more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form increasing concentration

4. Solubility A solution that contains the maximum possible amount of solute is saturated. If a solution contains less than the maximum amount of solute, it is unsaturated.

5. Solubility When a solution is saturated and excess solute is present, the rate of dissolution is equal to the rate of crystallization. Solubility increases with increasing temperature — a saturated solution that was prepared at a higher temperature contains more dissolved solute than it would contain at a lower temperature, when the solution is cooled, it can become supersaturated.

6. Hotpack / Coldpack

7. Hot and Cold Packs Article KeysKeys Article "Hot and Cold Packs" ChemMatters Feb. 1987 QuestionsQuestions Article "Hot and Cold Packs" ChemMatters Feb. 1987 QuestionsQuestions http://www.unit5.org/chemistry/Solutions.html

8. Solubility vs. Temperature Timberlake, Chemistry 7 th Edition, page 297 KI NaNO 3 KNO 3 Na 3 PO 4 NaCl Temperature ( o C) Solubility (g solute / 100 g H 2 O) 200 180 160 140 120 100 80 60 40 20 0 406080100

9. Gas Solubility CH 4 O2O2 CO He Temperature ( o C) Solubility (mM) 2.0 1.0 01020304050 Higher Temperature …Gas is LESS Soluble

10. Solubility Table LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World, 1996, page 517 0 10 20 30 40 50 60 70 80 90 100 Solubility vs. Temperature for Solids Solubility (grams of solute/100 g H 2 O) KI KCl 20 10 30 40 50 60 70 80 90 110 120 130 140 100 NaNO 3 KNO 3 HClNH 4 Cl NH 3 NaCl KClO 3 SO 2 shows the dependence of solubility on temperature gases solids

11. Solubility Solubility maximum grams of solute that will dissolve in 100 g of solvent at a given temperature – Solubility is expressed as (g/L) or (g/g) or (mol/L). varies with temperature based on a saturated solution

12. Solubility  Solids are more soluble at... high temperatures.  Gases are more soluble at... low temperatures & high pressures (Henry’s Law). EX: nitrogen narcosis, the “bends,” soda

13. Temp. ( o C) Solubility (g/100 g H 2 O) KNO 3 (s) KCl (s) HCl (g) SOLUBILITY CURVE Solubility  how much solute dissolves in a given amt. of solvent at a given temp. below Unsaturated: solution could hold more solute; below line on saturated: solution has “just right” amt. of solute; on line supersaturated: solution has “too much” solute dissolved in it; above the line

14. ToTo Sol. ToTo Solids dissolved in liquids Gases dissolved in liquids As T o, solubility

15. per 100 g H 2 O Classify as unsaturated, saturated, or supersaturated. 80 g NaNO 3 @ 30 o C 45 g KCl @ 60 o C 50 g NH 3 @ 10 o C 70 g NH 4 Cl @ 70 o C So sat. pt. @ 40 o C for 500 g H 2 O = 5 x 66 g = 330 g 120 g < 330 gunsaturated saturation point @ 40 o C for 100 g H 2 O = 66 g KNO 3 Per 500 g H 2 O, 120 g KNO 3 @ 40 o C unsaturated saturated unsaturated supersaturated

16. Solubility of Sodium Acetate Temperature ( o C) 0 255075100 Solubility(g/100 g H 2 O) 50 100 150 Supersaturated solution Unsaturated solution Saturated Video Clip Charles H.Corwin, Introductory Chemistry 2005, page 378 A single crystal of sodium acetate, NaC 2 H 3 O 2, is dropped into a supersatureated solution The small crystal causes extensive crystallization, and eventually the solute forms a solid mass of NaC 2 H 3 O 2.