1. Solutions and Solubility Chapter 8

2. What is a solution? homogeneous mixture; uniform throughout solvent is present in larger amount solute refers to what is dissolved a given solution can be made up of different amounts of solute and solvent eg 0.10 mol/L NaCl(aq); 0.50 mol/L NaCl(aq)

3. Some types of Solutions solutesolventexamples gasgasair, natural gas gasliquidO 2 (aq)—fish breathe this; CO 2 (aq) in carbonated drinks liquidgaswater vapour in air liquidliquidethanol(aq)—vodka antifreeze(aq) liquidsolidamalgam—Hg(Au) solidliquidtea(aq) solidsolidalloys—coins

4. Be careful with antifreeze... Aqueous solutions of ethylene glycol, CH 2 (OH)CH 2 (OH)(aq), aka antifreeze, are coloured fluorescent green. Why? Easy identification of a spill. Antifreeze has a sweet taste and can be attractive to pets. As little as one teaspoon of antifreeze can be deadly to a cat; similarly for dogs.

5. Composition of dry air: 78% N 2 21% O 2 0.9 % Ar CO 2 0.03% What is the solvent in air? N2N2

6. What governs solubility? Like dissolves like. Polar dissolves polar; i.e. Many ionic salts are water soluble due to ion-dipole attractions. For non-ionic solutes, in water, don’t forget possibility of hydrogen bonding. Non-polar dissolves non-polar.

7. Important definition: Miscible refers to liquids that are mutually soluble in any proportion. eg. Ethanol and water are soluble in any combination.

8. Water Solubility of Some Ionic Solutes as a Function of Temperature

9. Unsaturated, Saturated, Supersaturated Solutions A saturated solution is formed when no more solute will dissolve in a given amount of solvent, at a certain temperature. What will happen if additional solute is added to a saturated solution? The “excess” solute will not dissolve. It will usually sink.

10. An unsaturated solution can dissolve more solute at a given temperature. What will you observe if additional solute is added to an unsaturated solution? It will dissolve. A supersaturated solution contains more dissolved solute than it is “allowed” to have dissolved at a given temperature. Let’s do the lab...

11. Homework Brief, point-form answers to p 357 – Learning Check 1 to 6 RQs – 1 to 9, 13, 15 Let’s look at an interesting problem...

12. In 1989, the oil tanker Exxon Valdez struck a reef in Prince William sound, Alaska. The accident released 40 million litres of crude oil, eventually covering 26,000 km 2 of water. What was the average depth of the oil slick? What additional information is required to solve this problem? Assume average density of crude oil to be 0.86 g/mL; 1 L = (10 cm) 3

13. Exxon Valdez Oil Spill: Calc. average thickness of oil slick: V oil = 40E06 L area = 26E03 km 2 oil slick as shape of a rectangular prism: Volume = area * thickness What do we need to do with the units of area and volume, above?

14. Get consistent units for volume and area: V oil =40E06 L ↓ /1000L·m -3 40E03 m 3 A = 26,000 km 2 * (1000 m) 2 /km 2 = 2.6E10 m 2 Volume = A * thickness thickness = V/A = 40E03 m 3 / 2.6E10 m 2 = 1.5E-06 m or 1.5E-03 mm is thickness of oil slick.