The Mole - Chapter 7
Name:
Honors Chemistry
Mole Concept:
1. How many atoms of carbon are in five molecules of propane (C3H8)?
2. How many atoms of hydrogen are in five moles of propane(C3H8)?
3. How many moles of carbon are in five moles of propane (C3H8)?
4. The mass, in grams, of one mole of sodium atoms is
.
5. The mass, in grams, of one sodium atom is
.
6. One mole of CO2 contains
molecules of CO2.
7. One mole of CO2 contains
grams of CO2.
8. One mole of CO2 contains
9. The molar mass of CO2 is
atoms of carbon.
.
10. One mole of CO2 contains
atoms of oxygen
11. Two moles of MgSO4·7H2O contains
moles of water.
12. Two moles of MgSO4·7H2O contains
atoms of oxygen.
13. Two moles of MgSO4·7H2O contain
moles of magnesium.
14. Two moles of MgSO4·7H2O contain
grams of MgSO4·7H2O
15. What is the mass of 6.022 x 1023 molecules of water?
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16. What is the molar mass of aluminum chromate?
17. What is the mass of 1 mol Be(OH)2?
18. What is the mass of 6.022 x 1023 atoms of phosphorus?
19. What is the molar mass of zinc acetate?
Mole Conversions: Show the complete dimensional analysis setup. Include proper units and significant
figures in the answers.
20. Convert to moles:
a. 4.9 x 1021 molecules of CH3Br
b. 11.96 g sodium hydroxide
c. 0.0987 g dinitrogen pentoxide
21. Convert to grams:
a. 2.036 x 1022 molecules of sulfur dioxide
b. 0.0992 moles calcium chloride
c. 1.08 x 1024 formula units of aluminum sulfate
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22. Convert to number of particles (identify the appropriate particle):
a. 0.01589 g CH4
b. 3.6 mol lithium nitrate
c. 15.09 grams of potassium chlorate
23. The following questions are based on the compound potassium phosphate.
a. What is the molar mass of the compound?
b. How many moles are in 23.6 g of this compound?
c. How many formula units are in 15.99 mol?
d. How many grams are in 1.335 x 1024 formula units?
e. How many oxygen atoms are in 16 g of the compound?
f. How many grams of potassium are in 20.3 g of the compound?
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24. How many oxygen atoms are in 5.21 mol sulfuric acid?
25. How many carbon atoms are in 2.34g C3H6?
26. How many moles of nitrogen are in 6.55 x 1023 formula units of magnesium nitride?
27. How many protons are in 13.6 kg of silver?
Molar Volume of Gases at STP
28. How many moles of CO2 are in 3.97 L CO2 at STP?
29. What is the mass of 2.036 L of sulfur dioxide at STP?
30. How many molecules of chlorine are in 15.09 L of Cl2 at STP?
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31. Determine the volume of each of the following gases at STP.
a. 0.945 g carbon monoxide
b. 8.44 x 1022 molecules of hydrogen sulfide
c. 11.6 mol dinitrogen pentoxide
32. How many hydrogen atoms will be in 15.33 L of NH3 at STP?
33. The volume of a sample of fluorine gas at STP is measured to be 45.9 mL. How many fluorine atoms
are present in the sample?
Ideal Gas Law
34. What pressure is required for 0.230 moles of Argon to occupy a volume of 1.50 L at 30.0 °C?
35. What is the Celsius temperature of 0.987 g of NO2 at 728 mmHg if it has a volume of 568 mL?
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36. How many grams of nitrogen occupy a volume of 154 mL at 746 torr and 25°C?
37. How many grams of pentene, C5H10, occupy a volume of 36.9 mL at 158 kPa and 72°C?
38. Determine the molar mass of an unknown gas if a 1.08 g sample occupies a volume of 59.3 mL at
33°C and 746 mm Hg.
39. What is the pressure of 2.94 g of ethane, C2H6, if it has a volume of 83.2 mL at −24°C?
40. Determine the molar mass of a gas collected over water in a eudiometer equilibrated with the
atmosphere given the following data:
Mass of gas:
0.0835 g
Water Temperature:
60.0°C
Barometric Pressure:
752.8 torr
Volume of trapped gas:
34.9 mL
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41. Determine the density of the following gases:
a. fluorine at STP
b. sulfur trioxide at 60.0°C and 165.2 kPa.
42. At what temperature will chlorine gas at 722 mmHg have a density of 1.48 g/L?
Empirical and Molecular Formulas:
43. A compound is analyzed and is determined to consist of 1.723g of carbon, 0.288g of hydrogen and
0.459g of oxygen. What is the empirical formula of the compound?
44. Determine the empirical formula of a compound that is 24.74% potassium, 34.76% manganese, and
40.50% oxygen.
45. An unknown compound is analyzed. Its composition was determined to be 51.85% carbon, 8.64%
hydrogen and 39.51% oxygen. What is the empirical formula?
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46. Determine the empirical formula of a compound that is 20.23% aluminum and 79.77% chlorine.
47. Determine the molecular formula of a compound that contains and 84.21% carbon and 15.79%
hydrogen . The molar mass of the compound is 114.0g/mol.
48. Find the molecular formula of a compound with a molar mass of 283.9 g/mol that is composed of
43.64g of phosphorous and 56.36g of oxygen.
49. A compound is found to be 47.1% carbon, 6.54%H, and 46.4% chlorine. The rate of effusion of this
compound in the gaseous state was measured relative to oxygen gas. Oxygen was found to effuse at
rate that was 2.19 times faster than this compound. Determine the molecular formula of the
compound.
50. Laundry detergent is Na2CO3 • x H2O. When 2.558 g of the hydrate is heated, 0.948 g of the
anhydrous sodium carbonate remains. What is the value of x?
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Percent composition, empirical and molecular formulas:
51. Calculate the percent composition of lead(IV) phosphate
52. How many grams of nitrogen atoms are in 2.49 grams of calcium nitride?
53. Calculate the percent water in calcium chloride dihydrate.
54. Determine the empirical formula of a compound composed of 63.2 % carbon, 5.3 % hydrogen and
31.6 % oxygen.
55. An unknown gas is determined to have an empirical formula of CH2. If a 0.176 g sample of this gas
occupies a volume of 35.0 mL at 134 kPa and 175°C, determine its molecular formula.
56. Chemical analysis of an unknown compound indicated that the compound consisted of 54.6 % carbon,
9.0 % hydrogen and 36.4 % oxygen. The molar mass of the compound was found to be 176 g/mol.
Determine the molecular formula.
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57. Epsom salts is MgSO4 • x H2O, where x is a whole number. When 5.061 g of the hydrate is heated,
2.472 g of the anhydrous compound remains. Calculate the value of x.
Solution Concentration: Molarity and Molality
58. Determine the molarity of 350. mL of a solution containing 12.0 g of sucrose, C12H22O11.
59. What is the molarity of the solution formed by mixing 0.20 mol of sodium hydroxide with enough
water to make 150. ml of solution?
60. A solution is prepared by combining 21.5 g of CaCl2 with 63.0 g of water. The solution is found to
have a density of 1.20 g/mL. Determine the percent, molarity and molality of this solution.
61. How many grams of potassium chloride are needed to prepare 0.750 L of a 1.50 M solution of
potassium chloride in water?
62. 400. mL of a 0.20 M solution is determined to contain 13.6 g of some unknown solute. What is the
molar mass of this solute?
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63. How much water needs to be added to 15.9 g of potassium nitrate to make a solution that is 1.25 m?
64. What is the molality of a 17.87% aluminum sulfate solution?
65. 123g of sucrose is dissolved in 568g of water. The solution has a density of 1.34g/ mL. Determine
the molarity, molality, and percent by mass of the solution.
Review:
66. Determine the mass of:
a. 3.00x1020 N2O molecules
b. 0.00300 mol N2O molecules
c. 1.32 mol N2O
d. N2O that contains 0.00326 g of nitrogen atoms
e. 1.32 L N2O at STP
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67. Aspartame is an artificial sweetener that is 160 times sweeter than sucrose when dissolved in water. It
is marketed as Nutra-Sweet. The molecular formula of aspartame is C14H18N2O5.
a. What is the molar mass of aspartame?
b. How many moles of molecules are present in 10.0 g of aspartame?
c. Calculate the mass of 1.56 mol aspartame.
d. How many molecules are in 5.0 mg aspartame?
e. How many nitrogen atoms are in 1.2 g of aspartame?
f. What is the mass of 1.0 x 109 molecules of aspartame?
g. What is the mass, in grams, of 1 molecule of aspartame?
h. What is the mass, in amu, of 1 molecule of aspartame?
68. How many protons are in 891 mg of aluminum sulfate?
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69. In 1987, the first substance to act as a superconductor at a temperature above that of liquid nitrogen
(77 K) was discovered. The formula of this substance is YBa2Cu3O7. What is the percent
composition of this compound?
70. How many grams of oxygen can be found in 15.26 g of aluminum dichromate?
71. How many grams of fluorine gas would occupy a volume of 151 mL at 45°C and 720 torr?
72. What is the molar mass of 0.296 g of a gas that occupies 69.8 mL at 723 mm and 37°C?
73. A 12.0g sample of butadiene gas occupies a volume of 4.16 liters measured at 97°C and 1.62 atm. If
butadiene is composed of 88.89% carbon and 11.11% hydrogen, determine the molecular formula.
74. In an experiment, concentrated hydrochloric acid was reacted with aluminum. Hydrogen gas was
evolved and was collected over water at 25°C. It had a volume of 355 mL. The barometer read 750.0
mmHg. How many moles of hydrogen were collected?
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75. Determine the density of CO at STP.
76. What is the relative rates of effusion of nitrogen gas and a different gas that has a density of 1.29 g/L
at 115 kPa and 37°C?
77. How many molecules of N2O5 would occupy a volume of 765 mL at a pressure of 1343 mm and a
temperature of 78°C?
78. A 13.5 g sample of water at 30.0°C is heated to 130.0°C at standard pressure.
a. How much energy is required to achieve this?
b. What volume will the steam occupy at these conditions?
79. The compound adrenaline contains 56.79% carbon, 6.54 % hydrogen, 28.39% oxygen and 8.28%
nitrogen by mass. What is the empirical formula of adrenaline?
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80. A compound containing only sulfur and nitrogen is 69.6 % S by mass. A 0.865 g sample of this
compound is vaporized at 372°C and is found to occupy a volume of 249 mL at standard pressure.
Determine the empirical and molecular formulas for this compound.
81. A hydrocarbon compound is found to be 85.71% carbon and 14.29% hydrogen by mass. When
vaporized at 35ºC, 0.136 g of the compound occupies a volume of 45.0 mL and exerts a pressure of
691 torr.
82. What is the molality of a 15.66 % Na2SO4 solution?
83. How many grams of aluminum sulfate are required to make 500. mL of a 0.250 M solution?
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84. A solution with a total mass of 76.3 g contains 29.1 g of sucrose. Calculate the molality of the
solution.
85. A hydrocarbon fuel (contains only carbon and hydrogen) is burned and is completely converted into
carbon dioxide and water. If 2.641 g of carbon dioxide and 1.442 g of water are produced, what is the
empirical formula of the compound?
Cumulative Review Questions
86. An amorphous solid is placed into a graduated cylinder with 13.6 mL of water. The combined mass
of the water and solid is 20.47 grams and the combined water and solid volume is
15.2 mL.
What is the density of the solid in lbs/m3? Report the answer using appropriate sig figs and scientific
notation.
87. Sate the number of p+, n0, and e− in each of the following:
a. 67Zn2+
b. 91Y3+
c.
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As3−
88. Classify the following as element, compound, mixture (hetero) or solution.
Classification
gasoline
potting soil
orange juice with pulp
zirconium
baking soda
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212
89. A sample of
At undergoes an alpha decay and electron capture. Write the nuclear equations that
represent this process.
90. A sample of cadmium-115 has a half-life of 53.5 hours. The original sample mass was measured to
be 16.47 μg and after a certain amount of time the sample was found to have a mass of 0.515 μg.
How many days had the sample been undergoing radioactive decay?
91. Write the appropriate name or formula for each of the following.
(NH4)2CrO4
tetraphophorus decoxide
FeCl3 • 3 H2O
tungsten(VI) phosphite
Cl2O7
vanadic acid
H2TeO3
copper(II) chloride dihydrate
Os(CO3)2
arsenous acid
H3As(aq)
aluminum oxalate
92. A sample of pure aluminum contains 5.234 x 1024 protons. What is the mass of the sample?
93. A 41.3 gram sample of water vapor has a temperature of 126.8°C and a pressure of 1.16 atm. The
heat lost by the cooling of 7.46 grams of liquid water at 0°C is transferred to the water vapor, causing
its pressure to change to 1170 torr and its volume to become 133 mL. What was the initial volume of
the gas, in yds3?