1. Warm up 1-26-16 1. Changing from a gas to a liquid is called_____ 2. Freezing water is endothermic or exothermic? 3. How much heat is needed to convert 100 g of liquid water to steam from 99 °C to 111 °C? Agenda -Quiz Unit 6 -Go over homework WS -Notes unit 6-5 -Online HW Homework Jan 29 – Online HW Feb 1 – Test & Notebook ΔH fus Ice melting = 334 J/g ΔH vap Water boiling= 2260 J/g Cp of water vapor = 1.89 J/g·C Cp of water liquid = 4.18 J/g·C Cp of water ice = 2.05 J/g·C Reference

2. Quiz Topics  Phase change – i.e. sublimation gain/lost energy?  Endothermic/exothermic  Celsius and Kelvin  Specific heat problems ΔHΔHΔHΔH DO NOT Write on the quiz You may use a calculator Record your name and Quiz version

3. Answers Latent Heat WS 1) 36,740 J 2) 58760 J 3) Step 1: Q = 15 x 77 x 4.18 = 4827.9 Step 2: Q = 2260 x 15 = 33900 Step 3: Q = 15 x 70 x 1.89 = 1984.5 Answer = 40712.4 J 4) Step 1: Q = 15 x 3 x 2.05 = 92.25 Step 2: Q = 334 x 15 = 5010 Step 3: Q = 15 x 42 x 4.18 = 2633.4 Answer =7735.65 J 10) 11725 J 11) -7688.34 J 12) 254 J/C· mol 13) -1659.6 J this is an exothermic reaction 14) -7.98 Celsius

4. Unit 6-5 Phase Equilibrium

5. Phase Equilibrium   Phase Equilibrium: When particles are moving between two phases and no net change in the amount of either phase occurs. This can only be achieved in a closed system!

6. Phase Equilibrium

7. Slow Cooker vs. Pressure Cooker

8. Vapor Pressure   Vapor pressure: tendency of particles to escape from the liquid or solid (evaporation rate)   Must be in equilibrium   Increases with temperature

9. Phase Diagrams   Show relationship between pressure and temperature   Unique for each substance

11. Phase Diagrams   Triple point: the temp. and pressure when all 3 phases coexist at equilibrium.   Critical point: when gas and liquid states become identical (one phase)

12. Supercritical fluid   Video   http://www.youtube.com/watch?v=tgHhLKlRzJM

13. Check in Questions

14. Assignments  Notes Summary  Online HW due Friday