Chapter 3 1 Which one of the following statements about balanced equations

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Chemistry, 6e (McMurry/Fay)

Chapter 3 Formulas, Equations, and Moles

3.1 Multiple-Choice Questions

1) Chemical equations are balanced in order to obey the law of

A) definite proportions.

B) mass action.

C) mass conservation.

D) multiple proportions.

2) Which one of the following statements about balanced equations is false?

In a balanced reaction

A) atoms must be balanced on both sides of the reaction arrow.

B) mass must be conserved.

C) molecules must be balanced on both sides of the reaction arrow.

D) net charge must be balanced on both sides of the reaction arrow.

3) Which one of the following statements about balanced equations is true? A reaction is balanced by

A) changing the charge on an ion.

B) changing the formula of the molecule.

C) multiplying by suitable coefficients.

D) rearranging atoms in a molecule.

4) What is the stoichiometric coefficient for oxygen when the following equation is balanced using the

lowest whole-number coefficients

_____ C3H8O(l) + _____ O2(g) → _____ CO2(g) + _____ H2O(l)

A) 3

B) 5

C) 7

D) 9

5) What is the sum of the coefficients when the following equation is balanced using the lowest whole-

numbered coefficients?

_____ PH3(g) + _____ O2(g) → _____ P4O10(s) + _____ H2O(g)

A) 10

B) 12

C) 19

D) 22

6) What is the sum of the coefficients when the following equation is balanced using the lowest whole-

numbered coefficients?

_____ B2O3(s) + _____ HF(l) → _____ BF3(g) + _____ H2O(l)

A) 8

B) 11

C) 15

D) none of these

7) Aluminum metal reacts with iron(II) sulfide to form aluminum sulfide and iron metal. What is the

stoichiometric coefficient for aluminum when the chemical equation is balanced using the lowest whole-

number stoichiometric coefficients?

A) 1

B) 2

C) 3

D) 4

8) Calcium phosphate reacts with sulfuric acid to form calcium sulfate and phosphoric acid. What is the

stoichiometric coefficient for sulfuric acid when the chemical equation is balanced using the lowest

whole-number stoichiometric coefficients?

A) 1

B) 2

C) 3

D) none of these

9) Given the chemical equation: N2 + 3 H2 → 2 NH3. On a molecular level, what do the coefficients

mean?

A) 1 atom of nitrogen reacts with 3 atoms of hydrogen to give 2 atoms of ammonia.

B) 28 g of nitrogen reacts with 6 grams of hydrogen to give 34 grams of ammonia.

C) 1 mole of nitrogen reacts with 3 moles of hydrogen to give 2 moles of ammonia.

D) 1 molecule of nitrogen reacts with 3 molecules of hydrogen to give 2 molecules of ammonia.

10) Given the chemical equation: N2 + 3 H2 → 2 NH3. On a macroscopic level, what do the

coefficients mean?

A) 1 atom of nitrogen reacts with 3 atoms of hydrogen to give 2 atoms of ammonia.

B) 1 mole of nitrogen reacts with 3 moles of hydrogen to give 2 moles of ammonia.

C) 1 molecule of nitrogen reacts with 3 molecules of hydrogen to give 2 molecules of ammonia.

D) All of these are true.

11) Which conducts electricity?

A) A large collection of iron atoms

B) A single iron atom

C) Both a large collection of iron atoms and a single iron atom

D) Neither a large collection of iron atoms nor a single iron atom

12) 1.00 mole of O2 contains the same number of molecules as

A) 0.667 mole of O3.

B) 1.00 mole of CH3CO2H.

C) 2.00 mole of CH3CH2OH.

D) All of these

13) 1.00 mole of O2 contains the same number of oxygen atoms as

A) 0.667 mole of O3.

B) 1.00 mole of CH3CO2H.

C) 2.00 mole of CH3CH2OH.

D) All of the above

14) Which represents one formula unit?

A) One H

B) One H2

C) One NaH

D) All of these

15) Which is a formula mass?

A) 1.0 amu of H

B) 2.0 amu of H2

C) 24.0 amu of NaH

D) All of these

16) Which contains Avogadro’s number of formula units?

A) 36.5 g of Cl

B) 36.5 g of Cl2

C) 36.5 g of HCl

D) All of these

17) What is the molar mass of aspartic acid, C4O4H7N?

A) 43 g/mol

B) 70 g/mol

C) 133 g/mol

D) 197 g/mol

18) What is the molar mass of Co(NO3)2?

A) 90 g/mol

B) 121 g/mol

C) 152 g/mol

D) 183 g/mol

19) What is the molar mass of calcium permanganate?

A) 159 g/mol

B) 199 g/mol

C) 216 g/mol

D) 278 g/mol

20) What is the molar mass of hydrogen gas?

A) 1.00 g/mol

B) 2.00 g/mol

C) 6.02 × 1023 g/mol

D) 1.20 × 1023 g/mol

21) What is the mass of a single chlorine molecule, Cl2?

A) 5.887 × 10-23 g

B) 1.177 × 10-22 g

C) 35.45 g

D) 70.90 g

22) What is the mass of 0.500 mol of dichlorodifluoromethane, CF2Cl2?

A) 4.14 × 10-3 g

B) 60.5 g

C) 121 g

D) 242 g

23) How many moles are in 1.50 g of ethanol, CH3CH2OH?

A) 0.0145 mol

B) 0.0326 mol

C) 30.7 mol

D) 69.0 mol

25) What is the mass of 8.50 × 1022 molecules of NH3?

A) 0.00830 g

B) 0.417 g

C) 2.40 g

D) 120 g

26) How many oxygen atoms are in 3.00 g of sodium dichromate, Na2Cr2O7?

A) 0.0801 oxygen atoms

B) 9.85 × 1020 oxygen atoms

C) 6.90 × 1021 oxygen atoms

D) 4.83 × 1022 oxygen atoms

27) What is the identity of substance X if 0.380 mol of X weighs 17.5 g?

A) NO2

B) NO3

C) N2O

D) N2O4

28) What is the molar mass of butane if 5.19 × 1016 molecules of butane weigh 5.00 μg?

A) 58.0 g/mol

B) 172 g/mol

C) 232 g/mol

D) 431 g/mol

29) What mass of dinitrogen monoxide, N2O, contains the same number of molecules as 3.00 g of

trichlorofluoromethane, CCl3F?

A) 0.106 g

B) 0.961 g

C) 1.04 g

D) 9.37 g

30) What mass of sulfur hexafluoride, SF6, has the same number of fluorine atoms as 25.0 g of oxygen

difluoride, OF2?

A) 0.901 g

B) 8.33 g

C) 22.5 g

D) 203 g

31) How many chloride ions are in 1.50 mol of aluminum chloride?

A) 3.00 chloride ions

B) 4.50 chloride ions

C) 9.03 × 1023 chloride ions

D) 2.71 × 1024 chloride ions

32) How many anions are in 0.500 g of MgBr2?

A) 1.64 × 1021 anions

B) 3.27 × 1021 anions

C) 2.22 × 1026 anions

D) 4.43 × 1026 anions

33) How many cations are in 10.0 g of sodium phosphate?

A) 3.67 × 1022 cations

B) 1.10 × 1023 cations

C) 9.87 × 1024 cations

D) 2.96 × 1025 cations

34) Which of the following has the greatest mass?

A) 6.0 × 1023 atoms of O

B) 3.0 × 1023 molecules of O2

C) 2.0 × 1023 molecules of O3

D) All have the same mass.

35) Which of the following has the greatest mass?

A) 6.02 × 1023 molecules of O2

B) 16.0 g of O2

C) 0.500 mol of O2

D) All of these have the same mass.

36) Which of the following has the smallest mass?

A) 3.50 × 1023 molecules of I2

B) 85.0 g of Cl2

C) 2.50 mol of F2

D) 0.050 kg of Br2

37) How many moles of CuO can be produced from 0.450 mol of Cu2O in the following reaction?

2 Cu2O(s) + O2(g) → 4 CuO(s)

A) 0.225 mol

B) 0.450 mol

C) 0.900 mol

D) 1.80 mol

38) How many moles of BCl3 are needed to produce 25.0 g of HCl(aq) in the following reaction?

BCl3(g) + 3 H2O(l) → 3 HCl(aq) + B(OH)3(aq)

A) 0.229 mol

B) 0.686 mol

C) 2.06 mol

D) 4.38 mol

39) How many grams of calcium chloride are needed to produce 10.0 g of potassium chloride?

CaCl2(aq) + K2CO3(aq) → 2 KCl(aq) + CaCO3(aq)

A) 0.134 g

B) 7.44 g

C) 14.9 g

D) 29.8 g

40) Balance the chemical equation given below, and determine the number of moles of iodine that reacts

with 10.0 g of aluminum.

_____ Al(s) + _____ I2(s) → _____ Al2I6(s)

A) 0.247 mol

B) 0.556 mol

C) 0.741 mol

D) 1.11 mol

41) Balance the chemical equation given below, and determine the number of grams of MgO needed to

produce 15.0 g of Fe2O3.

_____ MgO(s) + _____ Fe(s) → _____ Fe2O3(s) + _____ Mg(s)

A) 0.0877 g

B) 1.26 g

C) 3.78 g

D) 11.4 g

42) Dinitrogen monoxide gas decomposes to form nitrogen gas and oxygen gas. How many grams of

oxygen are formed when 5.00 g of dinitrogen monoxide decomposes?

A) 0.550 g

B) 1.82 g

C) 3.64 g

D) 7.27 g

43) The density of ethanol, C2H5OH, is 0.789 g/mL. How many milliliters of ethanol are needed to

produce 10.0 g of CO2 according to the following chemical equation?

C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(l)

A) 4.12 mL

B) 6.63 mL

C) 13.2 mL

D) 26.5 mL

44) When 10.0 g of calcium metal is reacted with water, 5.00 g of calcium hydroxide is produced. Using

the following balanced equation, calculate the percent yield for the reaction?

Ca(s) + 2 H2O(l) → Ca(OH)2(aq) + H2(g)

A) 13.5%

B) 27.1%

C) 50.0%

D) 92.4%

45) If the percent yield for the following reaction is 65.0%, how many grams of KClO3 are needed to

produce 42.0 g of O2?

2 KClO3(s) → 2 KCl(s) + 3 O2(g)

A) 69.7 g

B) 107 g

C) 165 g

D) 371 g

46) If the percent yield for the following reaction is 75.0%, and 45.0 g of NO2 are consumed in the

reaction, how many grams of nitric acid, HNO3(aq), are produced?

3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)

A) 30.8 g

B) 41.1 g

C) 54.8 g

D) 69.3 g

47) In the reaction between glucose and oxygen, 10.0 g of glucose reacts and 7.50 L of carbon dioxide is

formed. What is the percent yield if the density of CO2 is 1.26 g/L?

C6H12O6(s) + 6 O2(g) → 6 CO2(g) + 6 H2O(l)

A) 26.1%

B) 40.6%

C) 43.1%

D) 64.5%

48) When methane, CH4, undergoes combustion with oxygen, the usual products are carbon dioxide and

water. Carbon monoxide is formed when the limiting reactant is

A) carbon dioxide.

B) methane.

C) oxygen.

D) water.

49) 10 g of nitrogen is reacted with 5.0 g of hydrogen to produce ammonia according to the chemical

equation shown below. Which one of the following statements is false?

N2(g) + 3 H2(g) → 2 NH3(g)

A) 2.8 grams of hydrogen are left over.

B) Hydrogen is the excess reactant.

C) Nitrogen is the limiting reactant.

D) The theoretical yield of ammonia is 15 g.

50) 5.0 g of iron is reacted with 5.0 g of water according to the chemical equation shown below. Which

one of the following statements is false?

3 Fe(s) + 4 H2O(l) → Fe3O4(s) + 4 H2(g)

A) 6.91 g of Fe3O4 are produced.

B) 2.85 g of H2O are left over.

C) Mass is conserved in this reaction.

D) Water is the limiting reactant.

51) Which substance is the limiting reactant when 2.0 g of sulfur reacts with 3.0 g of oxygen and 4.0 g

of sodium hydroxide according to the following chemical equation:

2 S(s) + 3 O2(g) + 4 NaOH(aq) → 2 Na2SO4(aq) + 2 H2O(l)

A) S(s)

B) O2(g)

C) NaOH (aq)

D) None of these substances is the limiting reactant.

52) When 5.00 × 1022 molecules of ammonia react with 4.00 × 1022 molecules of oxygen according to

the chemical equation shown below, how many grams of nitrogen gas are produced?

4 NH3(g) + 3 O2(g) → 2 N2(g) + 6 H2O(g)

A) 1.16 g

B) 1.24 g

C) 2.79 g

D) 4.65 g

53) How many grams of the excess reagent are left over when 6.00 g of CS2 gas react with 10.0 g of Cl2

gas in the following reaction:

CS2(g) + 3 Cl2(g) → CCl4(l) + S2Cl2(l)

A) 2.42 g

B) 2.77 g

C) 3.58 g

D) 4.00 g

54) When silver nitrate reacts with barium chloride, silver chloride and barium nitrate are formed. How

many grams of silver chloride are formed when 10.0 g of silver nitrate reacts with 15.0 g of barium

chloride?

A) 8.44 g

B) 9.40 g

C) 11.9 g

D) 18.8 g

55) When iron(III) oxide reacts with hydrochloric acid, iron(III) chloride and water are formed. How

many grams of iron(III) chloride are formed from 10.0 g of iron(III) oxide and 10.0 g of hydrochloric

acid?

A) 11.1 g

B) 14.8 g

C) 20.3 g

D) 35.1 g

56) Balance the chemical equation given below, and calculate the volume of nitrogen monoxide gas

produced when 8.00 g of ammonia is reacted with 12.0 g of oxygen at 25°C? The density of nitrogen

monoxide at 25°C is 1.23 g/L.

_____ NH3(g) + _____ O2(g) → _____ NO(g) + _____ H2O(l)

A) 7.32 L

B) 11.1 L

C) 11.5 L

D) 18.8 L

57) Molarity is defined as

A) moles of solute per liter of solution.

B) moles of solute per liter of solvent.

C) moles of solvent per liter of solution.

D) moles of solvent per liter of solvent.

58) What is the concentration of FeCl3 in a solution prepared by dissolving 10.0 g of FeCl3 in enough

water to make 275 mL of solution?

A) 2.24 × 10-4 M

B) 0.224 M

C) 4.46 M

D) 4.46 × 103 M

59) How many grams of AgNO3 are needed to make 250. mL of a solution that is 0.135 M?

A) 0.0917 g

B) 0.174 g

C) 5.73 g

D) 9.17 g

60) What volume of a 0.540 M NaOH solution contains 15.5 g of NaOH?

A) 0.209 L

B) 0.718 L

C) 1.39 L

D) 4.78 L

61) What is the concentration of NO3– ions in a solution prepared by dissolving 15.0 g of Ca(NO3)2 in

enough water to produce 300. mL of solution?

A) 0.152 M

B) 0.305 M

C) 0.403 M

D) 0.609 M

62) If the reaction of phosphate ion with water is ignored, what is the total concentration of ions in a

solution prepared by dissolving 3.00 g of K3PO4 in enough water to make 350. mL of solution?

A) 0.0101 M

B) 0.0404 M

C) 0.162 M

D) 0.323 M

63) What is the concentration of an AlCl3 solution if 150. mL of the solution contains 250. mg of Cl–

ion?

A) 1.57 × 10-2 M

B) 3.75 × 10-2 M

C) 4.70 × 10-2 M

D) 1.41 × 10-1 M

64) Which contains the greatest number of chloride ions?

A) 25 mL of 2.0 M NaCl

B) 50 mL of 1.0 M CaCl2

C) 10 mL of 2.5 M FeCl3

D) All contain the same number of chloride ions.

65) When a 1.0 M solution of NaCl at 25°C is heated to 55°C, the

A) density decreases and the molarity decreases.

B) density decreases and the molarity increases.

C) density increases and the molarity decreases.

D) density increases and the molarity increases.

66) Which statement about diluted solutions is false? When a solution is diluted

A) the concentration of the solution decreases.

B) the molarity of the solution decreases.

C) the number of moles of solute remains unchanged.

D) the number of moles of solvent remains unchanged.

67) What is the concentration of HCl in the final solution when 65 mL of a 12 M HCl solution is diluted

with pure water to a total volume of 0.15 L?

A) 2.8 × 10-2 M

B) 5.2 M

C) 28 M

D) 5.2 × 103 M

68) How many milliliters of a 9.0 M H2SO4 solution are needed to make 0.25 L of a 3.5 M H2SO4

solution?

A) 0.097 mL

B) 0.64 mL

C) 97 mL

D) 640 mL

69) How many mL of a 0.175 M FeCl3 solution are needed to make 250. mL of a solution that is

0.300 M in Cl– ion?

A) 0.429 mL

B) 143 mL

C) 429 mL

D) It is not possible to make a more concentrated solution from a less concentrated solution.

70) A student dissolved 3.00 g of Co(NO3)2 in enough water to make 100. mL of stock solution. He

took 4.00 mL of the solution then diluted it with water to give 275 mL of a final solution. How many

grams of NO3– ion are there in the final solution?

A) 0.0148 g

B) 0.0296 g

C) 0.0407 g

D) 0.0813 g

71) A student prepared a stock solution by dissolving 20.0 g of KOH in enough water to make 150. mL

of solution. She then took 15.0 mL of the stock solution and diluted it with enough water to make 65.0

mL of a final solution. What is the concentration of KOH for the final solution?

A) 0.548 M

B) 0.713 M

C) 1.40 M

D) 1.82 M

72) How many milliliters of 0.260 M Na2S are needed to react with 25.00 mL of 0.315 M AgNO3?

Na2S(aq) + 2 AgNO3(aq) → 2 NaNO3(aq) + Ag2S(s)

A) 15.1 mL

B) 30.3 mL

C) 41.3 mL

D) 60.6 mL

73) How many grams of CaCl2 are formed when 35.00 mL of 0.00237 M Ca(OH)2 reacts with excess

Cl2 gas?

2 Ca(OH)2(aq) + 2 Cl2(g) → Ca(OCl)2(aq) + CaCl2(s) + 2 H2O(l)

A) 0.00460 g

B) 0.00921 g

C) 0.0184 g

D) 0.0217 g

74) When 125 mL of 0.500 M AgNO3 is added to 100. mL of 0.300 M NH4Cl, how many grams of

AgCl are formed?

AgNO3(aq) + NH4Cl(aq) → AgCl(s) + NH4NO3(aq)

A) 4.30 g

B) 8.96 g

C) 13.3 g

D) 25.8 g

75) How many milliliters of 0.200 M FeCl3 are needed to react with an excess of Na2S to produce 2.75

g of Fe2S3 if the percent yield for the reaction is 65.0%?

3 Na2S(aq) + 2 FeCl3(aq) → Fe2S3(s) + 6 NaCl(aq)

A) 50.9 mL

B) 86.0 mL

C) 102 mL

D) 203 mL

76) If 100. mL of 0.100 M Na2SO4 is added to 200. mL of 0.150 M NaCl, what is the concentration of

Na+ ions in the final solution? Assume that the volumes are additive.

A) 0.133 M

B) 0.167 M

C) 0.250 M

D) 0.350 M

77) How many milliliters of 0.550 M hydriodic acid are needed to react with 25.00 mL of 0.217 M

CsOH?

HI(aq) + CsOH(aq) → CsI(aq) + H2O(l)

A) 0.0158 mL

B) 0.101 mL

C) 9.86 mL

D) 63.4 mL

78) In an acid-base neutralization reaction 23.74 mL of 0.500 M potassium hydroxide reacts with 50.00

mL of sulfuric acid solution. What is the concentration of the H2SO4 solution?

A) 0.119 M

B) 0.237 M

C) 0.475 M

D) 2.11 M

79) Balance the chemical equation given below, and determine the number of milliliters of 0.0300 M

phosphoric acid required to neutralize 25.00 mL of 0.0150 M calcium hydroxide.

_____ Ca(OH)2(aq) + _____ H3PO4(aq) → _____ Ca3(PO4)2(s) + _____ H2O(l)

A) 1.69 mL

B) 8.33 mL

C) 12.5 mL

D) 18.8 mL

80) When 200. mL of ç M hydrochloric acid is added to 125 mL of 1.75 × 10-4 M Mg(OH)2, the

resulting solution will be

A) acidic.

B) basic.

C) neutral.

D) It is impossible to tell from the information given.

81) Which one of the following compounds contains the smallest percent oxygen by mass?

A) CO2

B) N2O4

C) P4O10

D) SO2

82) Which one of the following contains 35% carbon by mass?

A) C2H2

B) CH4

C) CH3F

D) CO2

83) Which of the following statements is false concerning the formula of a compound?

A) The empirical formula is the simplest whole numbered ratio of atoms in a compound.

B) The molecular formula is the true ratio of atoms in a compound.

C) The molecular formula and empirical formula can be identical.

D) The number of atoms in a molecular formula is always greater than the number of atoms in an

empirical formula.

84) What is the empirical formula for ethyl fluoride if the compound contains 49.97% carbon, 10.51%

hydrogen, and 39.52% fluorine by mass?

A) C2H5F

B) C4H10F2

C) C4H10F4

D) C25F2

85) What is the empirical formula for perfluoropropane if the compound contains 81% fluorine and 19%

carbon by mass?

A) CF3

B) C2F8

C) C3F8

D) C19F81

86) What is the empirical formula of a substance that contains 2.64 g of C, 0.444 g of H, and 3.52 g of

A) CH2O

B) C2H4O2

C) C2H4O3

D) C3H4O4

87) Which one of the following is not an empirical formula?

A) CHO

B) CH2O

C) C2H4O

D) C2H4O2

88) Which one of the following is an empirical formula?

A) C2F6

B) H2SO4

C) N2H4

D) P4O10

89) A compound responsible for the odor of garlic has a molecular weight of 146 g/mol. A 0.650 g

sample of the compound contains 0.321 g of carbon, 0.044 g of hydrogen, and 0.285 g of sulfur. What is

the molecular formula of the compound?

A) CH5S

B) C3H5S

C) C3H15S3

D) C6H10S2

90) Which statement about elemental analysis by combustion is not correct?

A) Carbon is determined from the amount of CO2 formed.

B) Hydrogen is determined from the amount of H2O formed.

C) Oxygen is determined from the amount of H2O formed.

D) Only carbon and hydrogen can be determined directly from CO2 and H2O.

91) In the combustion analysis of an unknown compound containing only carbon, hydrogen, and

oxygen, the grams of oxygen are found from the grams of

A) CO2 only.

B) H2O only.

C) CO2 and H2O only.

D) CO2, H2O and unknown compound.

92) Combustion analysis of an unknown compound containing only carbon and hydrogen produced

4.554 g of CO2 and 2.322 g of H2O. What is the empirical formula of the compound?

A) CH2

B) C2H5

C) C4H10

D) C5H2

93) Combustion analysis of 2.400 g of an unknown compound containing carbon, hydrogen, and oxygen

produced 4.171 g of CO2 and 2.268 g of H2O. What is the empirical formula of the compound?

A) C2H5O

B) C2H5O2

C) C2H10O3

D) C3H8O2

94) Combustion analysis of a 0.675 g sample of an unknown compound that contains only carbon,

hydrogen, and oxygen gives 0.627 g of CO2 and 1.534 g of H2O. The molecular mass of the unknown is

A) C3H6O.

B) C6H12O2.

C) C9H18O3.

D) unable to be determined from this data.

95) Isoeugenol is the compound which gives the characteristic odor to nutmeg and contains carbon,

hydrogen, and oxygen. If a 0.500 g sample of isoeugenol is combusted it gives 1.341 g of CO2 and

0.329 g of H2O. Isoeugenol has a molecular weight of 164 g/mol. What is the molecular formula of

isoeugenol?

A) C2HO

B) C5H6O

C) C8H4O4

D) C10H12O2

96) Molecular mass can be determined by

A) combustion analysis.

B) mass spectrometry.

C) titration.

D) weighing with an analytical balance.

97) Which of the following statements about mass spectrometry is false?

A) Mass spectrometry can be used to determine the molecular weight of a compound.

B) The curvature of the path in a magnetic field is determined by the mass of the ion.

C) The paths of heavier ions are deflected more strongly than the paths of lighter ions.

D) The sample is changed into positively charged ions.