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Module 13 Test Answers

A. True or False: 1 point each

1. T

2. F

3. T

4. T

5. F

6. T

7. F

8. T

9. T

10. T

11. T

12. T

13. T

14. T

15. F

16. T

17. F

18. T

19. F

20. F

B. Multiple Choice: 1 point each

21. c

22. d

23. e

24. a

25. c

26. d

27. b

28. a

29. c

30. d

31. d

32. a

33. a

34. a

35. a

36. d

37. c

38. b

39. c

40. d

C. Calculations/Equations:  5 points each  (Be sure to show the correct units in your answer and balance any equations!)

41. The ΔH° for this reaction is -178 kJ.

Determine the chemical equation.

CaO (s) + CO₂ à CaCO₃ (s)

Table 13.2 from Appendix A:

ΔH^o = [(1 mole) x (-1207 kJ/mole)] – [(1 mole) x (-635 kJ/mole) + (1 mole) x (-394 kJ/mole)] = - 178 kJ

42. Burning 250.0 g of ethane provides 1.19 x 10⁴kJ of energy.

Write a balanced chemical equation for the combustion of ethane:

2C₂H₆ (g) + 7O₂ (g) à 4CO₂ (g) + 6H₂O (g)

Calculate the ΔH of the reaction: (Hint: The standard enthalpy of formation on an element like O₂ is zero.)

ΔH^o = [(4 mole) x (-394 kJ/mole) + (6 mole) x (-242 kJ/mole)] - [(2 mole) x (-84.7 kJ/mole) + 0 kJ/mole] = - 2,859 kJ

Energy is a product in the reaction:

2C₂H₆ (g) + 7O₂ (g) à 4CO₂ (g) + 6H₂O (g) + 2859 kJ

Convert to moles of ethane:

250.0 g C₂H₆ x 1 mole C₂H₆ = 8.31 moles C₂H₆

1 30.1 g C₂H₆

2 moles of ethane give us 2,859 kJ of energy:

8.31 moles C₂H₆ x 2,859 kJ = 1.19 X 10⁴ kJ

1 2 moles g C₂H₆

Burning 250.0 g of ethane provides 1.19 x 10⁴kJ of energy.

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