1. Measuring Heat

2. Calorimeter

3. Measuring Heat A device for measuring amount of heat absorbed or released. Calorimeter

4. Measuring Heat Insulated container. Calorimeter

5. Measuring Heat Known quantity of water. Calorimeter 20 o 250 g

6. Unknown substance 50g 20 o 250 g

7. Unknown substance 50g c = q / m∆T 20 o 250 g

8. heat 50g c = q / m∆T 20 o 250 g

9. heat 90 o 50g c = q / m∆T 20 o 250 g

10. c = q / m∆T 20 o 90 o 50g 250 g

11. The change in temperature of the water will tell us the amount of heat released as the substance cools. c = q / m∆T 20 o 90 o 50g 250 g

12. The change in temperature of the substance as it cools is ∆T. c = q / m∆T 20 o 90 o 50g 250 g

13. The change in temperature of the substance as it cools is ∆T. The mass of the substance is m. 20 o c = q / m∆T 90 o 50g 250 g

14. 90 o c = q / m∆T 50g 250 g 20 o

15. mass of water = 250 g mass of substance = 50 g c = q / m∆T 20 o 250 g 90 o 50g

16. mass of water = 250 g ∆T for water = 10 o C mass of substance = 50 g ∆T for substance = 60 o C c = q / m∆T 30 o 250 g 30 o 50g

17. mass of water = 250 g ∆T for water = 10 o C heat = 2500 cal mass of substance = 50 g ∆T for substance = 60 o C c = q / m∆T 30 o 250 g 50g 30 o

18. mass of water = 250 g ∆T for water = 10 o C heat = 2500 cal heat = (2500)(4.184) J mass of substance = 50 g ∆T for substance = 60 o C c = q / m∆T 30 o 250 g 50g 30 o

19. mass of water = 250 g ∆T for water = 10 o C heat = 2500 cal heat = (2500)(4.184) J heat = 10,460 J mass of substance = 50 g ∆T for substance = 60 o C c = q / m∆T 30 o 250 g 50g 30 o

20. heat = 10,460 J mass of substance = 50 g ∆T for substance = 60 o C c = 10,460 J / (50g)(60 o C) c = q / m∆T

21. heat = 10,460 J mass of substance = 50 g ∆T for substance = 60 o C c = 10,460 J / (50g)(60 o C) c = 3.49 J/g o C. c = q / m∆T

22. Thermochemistry

23. 4Fe + 3O 2 → 2Fe 2 O 3 + heat

24. Thermochemistry 4Fe + 3O 2 → 2Fe 2 O 3 + heat heat + NH 4 NO 3 → NH 4 + + NO 3 -

25. Thermochemistry system

26. Thermochemistry surroundings

27. Thermochemistry universe

28. Thermochemistry universe = system + surroundings

29. Total amount of heat is impossible to define, Thermochemistry

30. Total amount of heat is impossible to define, but change in heat can be measured. Thermochemistry

31. q is heat q p is heat at constant pressure H is enthalpy ∆ H is change in enthalpy q p = ∆ H rxn Thermochemistry

32. For an exothermic reaction, ∆ H reactants > ∆ H products Thermochemistry

33. For an exothermic reaction, ∆ H reactants > ∆ H products For an endothermic reaction, ∆ H reactants < ∆ H products. Thermochemistry

34. Standard enthalpy of combustion ∆ H comb (kJ/mol) Thermochemistry

35. Standard enthalpy of vaporization ∆ H vap (kJ/mol) Thermochemistry

36. Standard enthalpy of condensation ∆ H vap = - ∆ H cond Thermochemistry

37. Standard enthalpy of fusion ∆ H fus (kJ/mol) Thermochemistry

38. Standard enthalpy of solidification ∆ H fus = - ∆ H solid Thermochemistry

39. The biologist’s question: Thermochemistry

40. The biologist’s question: Cellular respiration turns 1 mole of glucose into about 36 ATP. ∆H glucose = -1252 kJ/mol ∆H ATP = -30.5 kJ/mol How much energy is lost as heat in breaking down 1 mole of glucose? Thermochemistry

41. Homework: Page 498, problems 12-13 Page 500, questions 15-19