1. REPRESENTING ENTHALPY CHANGES

2. 1. ΔH Notation 2. Thermochemical Equation 3. Potential Energy Diagram

3.  the ΔH is written outside the balanced chemical equation RECALL: + ΔH means ENDOTHERMIC - ΔH means EXOTHERMIC

4. 2 SO 2 + O 2  2SO 3 ΔH = -197.8 kJ “When 2 moles of SO 2 react with 1 mole of O 2, 2 moles of SO 3 are produced and 197.8 kJ of energy are released.” 1)What is the molar enthalpy of formation for SO 3 ? 2)What will the ΔH be if 4 moles of SO 2 react with excess O 2 ?

5.  a balanced chemical equation which includes the ΔH for the rxn as either a reactant (LEFT side) or product (RIGHT side) exothermic - ΔH energy quantity as a PRODUCT endothermic +ΔH energy quantity as a REACTANT

6. 1) Write a thermochemical equation for the following: N 2 + 3H 2  2 NH 3 ΔH = -92.38 kJ (i.e., ΔH notation)

7. 2) Write the thermochemical equation using ΔH notation: CO 2 + 393.5 kJ  C + O 2 (i.e., thermochemical equation)

8.  all stoichiometric ratios apply to the energy component 2 Fe + 3 CO 2 + 6.39 kJ  Fe 2 O 3 + 3 CO “When 2 mol of Fe react with 3 mol of CO 2, 6.39 kJ of energy are consumed. 1 mol of Fe 2 O 3 and 3 mol of CO are produced”.

9. 1) Rewrite the thermochemical equation so that the coefficient in front of the Fe is a 1 2) How many kJ are required to completely react 8.00 g of Fe?

10. Exothermic Energy Rxn Coordinate

11. Exothermic Energy Rxn Coordinate

12. Exothermic Energy Rxn Coordinate Energy of the Reactants Energy of the products -ΔH energy released

13. Endothermic Energy Rxn Coordinate

14. Endothermic Energy Rxn Coordinate Energy of the Reactants Energy of the products +ΔH energy absorbed

15. Construct a PE diagram for the reaction: N 2 + O 2 + 180.8 kJ  2NO

16. Endothermic Energy Rxn Coordinate N 2 + O 2 2NO ΔH = 180.8 kJ