Chapter 03 – Mass Relationships in Chemical Reactions
48. How many moles of HCl are represented by 1.0 1019 HCl molecules?
49. How many sodium atoms are there in 6.0 g of Na3N?
50. How many moles of O are in 2.45 moles of H2CO3?
Chapter 03 – Mass Relationships in Chemical Reactions
52. How many moles of C are in 1.22 moles of C6H12O6?
53. How many sulfur atoms are there in 21.0 g of Al2S3?
Chapter 03 – Mass Relationships in Chemical Reactions
54. How many sulfur atoms are present in 25.6 g of Al2(S2O3)3?
55. How many fluorine atoms are there in 65 g of CF4?
56. How many moles of O atoms are in 25.7 g of CaSO4?
Chapter 03 – Mass Relationships in Chemical Reactions
57. How many O atoms are there in 51.4 g CaSO4?
58. How many moles of Cl atoms are there in 65.2 g CHCl3?
59. How many carbon atoms are there in 15 lbs of sugar, C12H22O11?
Chapter 03 – Mass Relationships in Chemical Reactions
60. Calculate the mass of O in 4.36 g of Cl2O7?
61. Calculate the mass of C in 5.46 g of C2H4?
62. Calculate the mass of N in 2.34 g of N2H4?
Chapter 03 – Mass Relationships in Chemical Reactions
63. How many grams of nitrogen are there in 7.5 g of Ca(NO3)2?
64. Calculate the mass of 4.50 moles of chlorine gas, Cl2.
65. What is the mass of 3.00 moles of ethanol, C2H6O?
Chapter 03 – Mass Relationships in Chemical Reactions
66. What is the mass of 0.55 mole of C6H6?
67. What is the mass of 8.25 1019 UF6 molecules?
Chapter 03 – Mass Relationships in Chemical Reactions
68. A mass spectrometer works by ionizing atoms or molecules, and then accelerating them
through oppositely charged plates. The mass is obtained by
69. The mineral pyrolusite is a compound of 55Mn and 16O. If 63% of the mass of pyrolusite is
due to manganese, what is the empirical formula of pyrolusite?
Chapter 03 – Mass Relationships in Chemical Reactions
70. The mineral manganosite is a compound of 55Mn and 16O. If 77% of the mass of
manganosite is due to manganese, what is the empirical formula of manganosite?
71. The mineral hausmannite is a compound of 55Mn and 16O. If 72% of the mass of
hausmannite is due to manganese, what is the empirical formula of hausmannite?
Chapter 03 – Mass Relationships in Chemical Reactions
72. Zircon is a mineral with the empirical formula ZrSiO4. If all the zirconium is 90Zr, all the
silicon is 28Si, and all the oxygen is 16O, what mass of oxygen is present in 10. g of zircon?
73. The mineral orpiment, having the empirical formula As2S3, was used in ancient times as a
cosmetic. What mass of arsenic is present in 5.0 g of orpiment? [Given: naturally occurring
arsenic is all arsenic-75; assume that all naturally occurring sulfur is sulfur-32 (only
Chapter 03 – Mass Relationships in Chemical Reactions
74. A compound with an empirical formula of C2H4Br has a molar mass of 215.90 g/mol.
What is the molecular formula?
75. A compound with an empirical formula of C2H3Br2 has a molar mass of 373.69 g/mol.
What is the molecular formula?
Chapter 03 – Mass Relationships in Chemical Reactions
76. A compound with an empirical formula of C2H2Br3 has a molar mass of 531.47 g/mol.
What is the molecular formula?
77. An unknown compound with a molar mass of 155.06 g/mol consists of 46.47% C, 7.80%
H, and 45.72% Cl. Find the molecular formula for the compound.
Chapter 03 – Mass Relationships in Chemical Reactions
78. An unknown compound with a molar mass of 223.94 g/mol consists of 32.18% C, 4.50%
H, and 63.32% Cl. Find the molecular formula for the compound.
79. The empirical formula of a compound of uranium and fluorine that is composed of 67.6%
uranium and 32.4% fluorine is
Chapter 03 – Mass Relationships in Chemical Reactions
80. The percent composition by mass of a compound is 76.0% C, 12.8% H, and 11.2% O. The
molar mass of this compound is 284.5 g/mol. What is the molecular formula of the
compound?
81. A compound was discovered whose composition by mass is 85.6% C and 14.4% H.
Which of the following could be the molecular formula of this compound?
Chapter 03 – Mass Relationships in Chemical Reactions
82. An organic thiol compound is 38.66% C, 9.73% H, and 51.61% S by mass. What is the
empirical formula of this compound?
83. The percent composition by mass of an unknown chlorinated hydrocarbon was found to
be 37.83% C, 6.35% H, and 55.83% Cl by mass. What is the empirical formula of this
compound?
Chapter 03 – Mass Relationships in Chemical Reactions
84. Which one of the following is an example of a balanced chemical reaction?
Chapter 03 – Mass Relationships in Chemical Reactions
85. Which one of the following is an example of a balanced chemical reaction?
Chapter 03 – Mass Relationships in Chemical Reactions
86. What is the coefficient of H2O when the following equation is properly balanced?
___ Al4C3 + ___ H2O → ___ Al(OH)3 + ___ CH4
87. When balanced the coefficient of O2 in the following equation is
__ C2H4 + __ O2 → __ CO2 + __ H2O
Chapter 03 – Mass Relationships in Chemical Reactions
88. What is the coefficient for O2 when the following combustion reaction of a hydrocarbon is
balanced?
___ C7H14 + ___ O2 → ___ CO2 + ___ H2O
89. What is the coefficient for O2 when the following combustion reaction of a fatty acid is
properly balanced?
__ C18H36O2 + __ O2 → __ CO2 + __ H2O
Chapter 03 – Mass Relationships in Chemical Reactions
90. What is the coefficient of H2SO4 when the following equation is properly balanced?
___ Ca3(PO4)2 + ___ H2SO4 → ___ CaSO4 + ___ H3PO4
91. What is the coefficient of H2O when the equation below is properly balanced?
___ PCl3(l) + ___ H2O(l) → ___ H3PO3(aq) + ___ HCl(aq)