1. Chemical Energy LO:I understand the energy changes involved in an exothermic reaction. 1.Exothermic Reactions

2. An reaction is a chemical change that gives out heat energy. is a measure of the chemical energy stored in substances. The symbol for enthalpy is and the units are. LO:I understand the energy changes involved in an exothermic reaction. exothermic Enthalpy HkJ

3. Experiment: Mg(s) + CuSO 4 (aq)Cu(s) + MgSO 4 (aq) When magnesium is added to copper ions, the temperature of the solution. This is an reaction. LO:I understand the energy changes involved in an exothermic reaction. increases exothermic

4. LO:I understand the energy changes involved in an endothermic reaction. 2.Endothermic Reactions

5. An reaction is a chemical change that takes in heat energy. LO:I understand the energy changes involved in an exothermic reaction. endothermic

6. Experiment: Ba(OH) 2 + 2NH 4 ClBaCl 2 + 2NH 3 + H 2 O When barium hydroxide is mixed with ammonium chloride, the temperature of the mixture. This is an reaction. LO:I understand the energy changes involved in an endothermic reaction. decreases endothermic

7. LO:I understand the energy changes involved in reactions. 3.Enthalpy Changes

8. LO:I understand the energy changes involved in reactions. The enthalpy change for a reaction is the difference between the total enthalpy of the and the total enthalpy of the. The symbol for enthalpy change is  and the units are.  H = products reactants HH kJ H(products) - H(reactants)

9. Exothermic reactionsEndothermic reactions  H = -969 - (-75) = -894 kJ  H = +53 - (-85) = +138 kJ  H is always negative  H is always positive LO:I understand the energy changes involved in reactions.