1. J Unit 4. Kinetics+Equilibrium 4.4 What is endothermic and exothermic reactions? March 15, 2011 Do Now: Going over questions from yesterday AIM: How do we distinguish between endothermic and exothermic reactions?

4. ENDOTHERMIC REACTIONS

5. DEFINITION reactions that take in energy (heat) heat is absorbed from the surroundings

6. EXAMPLES solid liquid (ice cream melting) liquid gas (boiling water) solid gas melting vaporization sublimation

7. Where is the heat? 2H2O(g) + heat 2H2(g) + O2(g) 2H2O(g) + 103 kJ 2H2(g) + O2(g) 2POCl3(g) + energy 2PCl3(g) + O2(g) Circle where the heat is located. Indicate whether it is a reactant or a product

8. KEY IDEA endothermic reaction sample absorbs heat heat is on the left side (reactant side)

9. EXOTHERMIC REACTIONS

10. DEFINITION Reactions that release energy (heat)

11. EXAMPLE gas liquid (rain) liquid solid (making ice cubes) gas solid condensation freezing deposition

12. Where is the heat? 8H 2 + S 8 8H 2 S + heat 8H 2 + S 8 8H 2 S + 1026 J Circle where the heat is located. Indicate whether it is a reactant or a product

13. KEY IDEA exothermic reaction sample releases heat heat is on the right side (product side)

14. INDEPENDENT PRACTICE 1.To be collected at the end of CLASS! 2.COME SEE ME AFTER SCHOOL IF YOU NEED TO MAKE UP WORK!