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34. The molecular formula of benzene, C 6 H 6 , tells us that benzene is 44. The iron in a scouring pad will react with oxygen in the air to form
composed of six carbon atoms and six hydrogen atoms. What is iron oxide, Fe 2 O 3 , rust. The type of reaction that is described is
the empirical formula of benzene? a. replacement.
a. C 3 H 3 b. combination.
b. C 6 H 6 c. decomposition.
c. C 2 H 2 d. ion exchange.
d. CH 45. What is the formula weight of magnesium hydroxide,
35. What is the formula weight of acetic acid, CH 3 COOH, which is an ingredient found in antacids?
found in vinegar? a. 41.3 u
a. 29.0 u b. 58.3 u
b. 48.0 u c. 72.0 u
c. 58.0 u d. 89.0 u
d. 60.0 u 46. An ion exchange reaction can be identified by all of the following
36. What are the coefficients needed to balance this chemical equation? except
CaCl 2 + KOH → Ca(OH) 2 + KCl a. formation of a precipitate.
a. 1, 2, 1, 2 b. generation of a gas.
b. 2, 1, 2, 1 c. formation of water.
c. 1, 1, 1, 2 d. the required addition of heat.
d. 2, 1, 1, 1 47. What are the coefficients needed to balance this chemical equation?
37. What class of chemical reactions is not considered to belong to C 2 H 6 (g) + O 2 (g) → CO 2 (g) + H 2 O(g)
the class of oxidation-reduction reactions? a. 1, 3, 2, 3
a. Combination b. 1, 5, 2, 3
b. Decomposition c. 2, 7, 4, 6
c. Ion exchange d. 2, 5, 4, 3
d. Replacement 48. What is the empirical formula of butane, C 4 H 10 ?
38. Which reaction is an example of a combination reaction? a. CH
a. 2 HgO(s) → 2 Hg(s) + O 2 (g) b. C 2 H 5
b. 4 Fe(s) + 3 O 2 (s) → Fe 2 O 3 (g) c. CH 3
c. CaCO 3 (s) → CaO(s) + CO 2 (g) d. C 4 H 10
d. Na(s) + KCl(aq) → K(s) + NaCl(aq) 49. How many moles of products are in this chemical equation?
39. To what chemical reaction class does this reaction belong?
CH 4 (g) + 2 O 2 (g) → CO 2 (g) + 2 H 2 O(g)
Fe(s) + CuSO 4 (aq) → Cu(s) + FeSO 4 (aq ) a. 2
a. Ion exchange b. 3
b. Combination c. 6
c. Replacement d. 6.02 × 10 23
d. Decomposition
Answers
40. How many liters of propane gas are needed to produce 16 L of
1. b 2. b 3. a 4. a 5. b 6. a 7. a 8. c 9. c 10. a 11. a 12. d 13. a 14. a
water vapor?
15. c 16. a 17. a 18. a 19. c 20. c 21. c 22. a 23. c 24. b 25. a 26. d
C 3 H 8 (g) + 5 O 2 (g) → 3 CO 2 (g) + 4 H 2 O(g) 27. b 28. d 29. a 30. d 31. b 32. c 33. b 34. d 35. d 36. a 37. c 38. b
a. 2 39. c 40. c 41. c 42. c 43. d 44. b 45. b 46. d 47. c 48. b 49. b
b. 3
c. 4
d. 16 QUESTIONS FOR THOUGHT
41. How many sodium atoms are in 2 moles of sodium?
a. 11 1. How is an empirical formula like and unlike a molecular formula?
b. 6.02 × 10 23 2. Describe the basic parts of a chemical equation. Identify how the
c. 1.20 × 10 24 physical state of elements and compounds is identified in an
d. 22 equation.
42. What is the gram-formula weight of sodium chloride? 3. What is the law of conservation of mass? How do you know if a
a. 23 u chemical equation is in accord with this law?
b. 23 g 4. Describe in your own words how a chemical equation is
c. 58. 5 g balanced.
d. 58. 5 u
5. What is a hydrocarbon? What is a carbohydrate? In general, what
43. A balanced chemical reaction provides all of the following are the products of complete combustion of hydrocarbons and
information except carbohydrates?
a. molecular ratio of reactants and products.
6. Define and give an example in the form of a balanced equation
b. mole ratio of reactants and products.
of (a) a combination reaction, (b) a decomposition reaction,
c. mass ratio of reactants and products.
(c) a replacement reaction, and (d) an ion exchange reaction.
d. exchange rate of reactants and products.

10-21 CHAPTER 10 Chemical Reactions 271