45) Which of the following contains as many atoms as 18 g of water, H2O?
A) one mole of nitrogen, N2
B) three moles of zinc, Zn
C) two moles of sodium chloride, NaCl
D) two moles of nitrogen, N2
46) How many moles of sulfur atoms are present in 4.00 moles of CS2?
A) 2.00
B) 4.00
C) 8.00
D) 12.00
47) What is the molecular mass of N2O?
A) 30 g/mole
B) 30 u
C) 44 g/mole
D) 44 u
48) How many molecules are in 237 g (about a cup) of water?
A) 13.1
B) 4267
C) 6.02 × 1023
D) 7.92 × 1024
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49) Nitroglycerin has a formula C3H5(NO3)3. The molar mass of nitroglycerin is
A) 65 g/mole.
B) 227 g/mole.
C) 309 g/mole.
D) 398 g/mole.
50) Aspirin has a formula C9H8O4. The molar mass of aspirin is
A) 95 g/mole.
B) 180 g/mole.
C) 220 g/mole.
D) 325 g/mole.
51) In the reaction CH4 + 2 O2 → CO2 + 2 H2O, how many moles of oxygen are required to burn 8.0 g
of methane?
A) 0.5
B) 1.0
C) 2.0
D) 32
52) In the reaction CH4 + 2 O2 → CO2 + 2 H2O, how many moles of oxygen are required to burn 16.0
g of methane?
A) 0.500
B) 1.00
C) 2.00
D) 32.0
Answer: C
Diff: 3 Var: 1 Page Ref: Sec. 5.4
Global Obj: Global 4: Demonstrate the quantitative skills needed to succeed in chemistry.
Learning Obj: LO 5.6 Calculate the mass or number of moles of a reactant or product from the mass or
number of moles of another reactant or product.
53) Acetylene (C2H2) burns in pure oxygen with a very hot flame. The products of this reaction are
carbon dioxide and water. How much oxygen is required to react with 52.0 g of acetylene?
A) 32.0 g
B) 52.0 g
C) 160. g
D) 240. g
54) Calcium metal reacts with water to form calcium hydroxide and hydrogen gas. How many grams of
hydrogen are formed when 0.50 g of calcium are added to water?
A) 0.025 g
B) 0.050 g
C) 0.10 g
D) 0.50 g
55) Joseph Priestley discovered oxygen in 1774 by heating mercury(II) oxide. The compound decomposes
into its elements. How much oxygen, O2, is produced by the decomposition of 25 g of HgO?
A) 1.8 g
B) 3.7 g
C) 5.5 g
D) none of these
56) Consider the following equation: N2 + 3 H2 → 2 NH3
Which of the following statements is NOT true for this equation?
A) 3 mole of N2 reacts with 9 moles of H2.
B) 1 L of N2 reacts with 3 L of H2.
C) 3 gram of N2 reacts with 9 grams of H2.
D) 2 molecule of N2 reacts with 6 molecules of H2.
57) What is the molar mass of N2O?
A) 30 g/mole
B) 30 u
C) 44 g/mole
D) 44 u
58) What is the mass of 0.500 mol of NH3?
A) 8.50 g
B) 3.40 g
C) 7.50 g
D) 34.0 g
59) How many moles of (NH4)2S are there in 75 g of (NH4)2S?
A) 1.04
B) 1.10
C) 1.50
D) 1.56
60) The quantitative relationship between reactants and products in a chemical reaction is
A) relative mass.
B) percent yield.
C) molarity.
D) stoichiometry.
61) What is the best way to measure the efficiency of a reaction?
A) experimental yield
B) percent atom economy
C) percent yield
D) theoretical yield
62) Atom economy is
A) the calculation of the number of atoms conserved in the desired product rather than in waste.
B) counting the atoms in the starting material and product.
C) having green by-products.
D) having green starting materials.
63) A one molar solution is a solution that contains one mole of solute in
A) one mole of solvent.
B) one liter of solution.
C) one kilogram of solvent.
D) one kilogram of solution.
64) A solution that is 1 molar contains
A) six moles of solute in 6 moles of solvent.
B) five moles of solute in 5 moles of solution.
C) six moles of solute in 600 g of solution.
D) four moles of solute in 4 liters of solution.
65) Molarity is a measure of
A) the volume of a solution.
B) the mass of a substance.
C) the ability of a substance to ionize.
D) the concentration of a solute in a solution.
66) Calculate the number of moles of sodium chloride needed to make 4.0 L of a 3.0 M solution.
A) 12 moles of sodium chloride
B) 3.0 moles of sodium chloride
C) 4.0 moles of sodium chloride
D) 7.0 moles of sodium chloride
67) Calculate the number of moles of sodium hydroxide present in 300 mL of a 2.0 M solution of sodium
hydroxide.
A) 600 moles of sodium hydroxide
B) 0.60 moles of sodium hydroxide
C) 300 moles of sodium hydroxide
D) 2.0 moles of sodium hydroxide
68) Expressing concentrations in terms of molarity is especially convenient since it allows one to count
chemical particles by measuring
A) the weights of solutes.
B) the weights of solutions.
C) the volumes of solvents.
D) the volumes of solutions.
69) A four molar solution of NaOH in water contains
A) four moles of NaOH per liter of solution.
B) four grams of NaOH per liter of solution.
C) four liters of NaOH per mole of solution.
D) four moles of NaOH per mole of solution.
70) The molarity of a solution that contains 0.50 moles of NaOH in 200.0 milliliters of water is
A) 0.25 M.
B) 0.5 M.
C) 1.0 M.
D) 2.5 M.
71) The molarity of a solution that contains 8.0 g of NaOH in a liter of solution is
A) 0.020 M.
B) 0.20 M.
C) 2.0 M.
D) 0.80 M.
72) The number of moles of NaOH that are in 250 mL of a 3.0 molar solution is
A) 0.25 moles.
B) 0.75 moles.
C) 1.0 moles.
D) 1.5 moles.
73) A solution that is 1% by mass contains
A) 3 g of solute in 3 kg of solution.
B) 1 g of solute in 100 g of solution.
C) 3 mL of solute in 300 mL of solution.
D) 2 mole of solute in 2 L of solution.
74) How many liters of a 0.2 M NaOH solution are needed in order to have 1.0 moles of NaOH?
A) 0.2 L
B) 0.8 L
C) 5 L
D) 8 L
75) How many mL of a 4.0% NaOH solution do you need to have 16 g of NaOH?
A) 160 mL
B) 250 mL
C) 400 mL
D) 640 mL
76) How many liters of a 0.2 M HCl solution are needed in order to have 1.0 moles of HCl?
A) 0.2 L
B) 0.8 L
C) 5 L
D) 8 L
77) A chemist dissolves 9 g of NaCl in 225 mL of water. Water is the
A) solution.
B) solute.
C) solvent.
D) solubility.
78) A solution contains 20 mL of ethanol in a total volume of 100 mL. The concentration of this solution is
A) 2.0 M.
B) 2.0 % by mass.
C) 20 % by mass.
D) 20 % by volume.
79) What mass of KOH is needed to make 400.0 mL of 0.725 M KOH?
A) 31.0 g
B) 101.7 g
C) 40.6 g
D) 16.3 g
5.2 True/False Questions
1) The reactants are the starting materials in a reaction.
2) In an equation, the number in front of a formula is the coefficient.
3) You can balance a chemical equation by changing the formula of a reactant or a product.
4) According to Avogadro’s hypothesis, equal volumes of gases at the same temperature and pressure
will have the same number of molecules.
5) The formula mass of Na2S is 55 u.
6) 50 grams of sodium hydroxide will react with 50 grams of hydrochloric acid to give 50 grams of
sodium chloride and 50 grams of water.
7) The molar mass of N2O is 44 u.
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8) The stoichiometric factor relates the moles of any two substances in a balanced chemical reaction.
9) An addition reaction will have a higher percent atom economy than a substitution reaction.
10) The percent atom economy is a measure of the proportion of the reactant atoms that become part of
the desired product.
11) 600 mL of a 5.0 M solution of sodium hydroxide contains 5.0 moles of sodium hydroxide.
12) The molarity (M) of a solution is the number of moles of solute per liter of solution.
13) When 15 mL of ethanol is mixed with 55 mL of water, ethanol is the solute.
14) The mass percent of a solution that has 0.50 mol of NaOH in 100 g of solution is 5.0%.
5.3 Essay Questions
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1) Balance the equation: AlCl3 + H2SO4 → Al2(SO4)3 + HCl.
2) Balance the equation: C8H18 + O2 → CO2 + H2O
3) Balance the equation: C3H8 + O2 → CO2 + H2O
4) Balance the equation: Zn + CuSO4 → ZnSO4 + Cu
5) Balance the equation: Cu + AgNO3 → Cu(NO3)2 + Ag
6) Balance the equation: Fe + O2 → Fe2O3
7) Balance the equation: NaCN + H2SO4 → Na2SO4 + HCN
8) Tin was among the first metals used by humans. Elemental tin is produced by heating tin(IV) oxide,
the principal ore of tin, with carbon. The products of this reaction are tin and carbon dioxide. Write and
balance the equation.
9) Ammonia can be prepared by the reaction of magnesium nitride with water. The products are
ammonia and magnesium hydroxide. Write and balance the equation.
10) When oxygen, O2, is passed through an electrical spark (lightning is a good natural source of an
electrical spark), ozone, O3 is formed. Write and balance the equation.