Question 1

One way of obtaining pure sodium carbonate is through the decomposition of the mineral trona, Na 3(CO3) (HCO3)  ×	imes× 2H2O, as shown in the following reaction: 2Na3(CO3) (HCO3)  →arr→ 2H2O(s)   →arr→ 3Na2CO3(s)  + CO2(g)  + 5H2O(g) 
When 15 metric tons (1 * 103 kg)  of trona is decomposed, 11 metric tons of Na2CO3 is recovered. What is the percent yield of this reaction?
(1 metric ton = 103 kg)

Accepted Answer

A)   13%
B)   42%
C)   65%
D)   73%
E)   95% F) D) and E)
G) A) and B)

Question 2

Acetylene gas, HCCH(g) , can be generated in the laboratory by adding calcium carbide to excess water, as shown in the following reaction 
CaC2(s)  + H2O(l)   →\rarr→  HCCH(g)  + CaO(s) 
How many grams of CaC2 would be required to generate 0.20 moles of HCCH(g)

Accepted Answer

A)   11 g of CaC2 would be required
B)   13 g of CaC2 would be required
C)   15 g of CaC2 would be required
D)   17 g of CaC2 would be required
E)   None of the above are correct F) A) and D)
G) A) and E)

Question 3

What is the mass of 3.50 x 1024 Ti atoms

Accepted Answer

A)   47.9 amu
B)   47.9 g
C)   5.81 g
D)   278 g
E)   5.81 amuF) B) and D)
G) A) and B)

Question 4

Determine the number of moles of aluminum in 96.7 g of Al.

Accepted Answer

A)   0.279 mol
B)   3.58 mol
C)   7.43 mol
D)   4.21 mol
E)   6.02 * 1023 molF) A) and B)
G) A) and D)

Question 5

When a 0.860 g sample of an organic compound containing C, H, and O was burned completely in oxygen, 1.64 g of CO2 and 1.01 g of H2O were produced. What is the empirical formula of the compound

Accepted Answer

A)   C2H6O
B)   C3H6O
C)   C3H8O
D)   C2H6O3
E)   None of the aboveF) B) and C)
G) A) and B)

Question 6

A compound with a percent composition by mass of 87.5% N and 12.5% H was recently discovered. What is the empirical formula for this compound

Accepted Answer

A)   NH2
B)   NH4
C)   N3H2
D)   N2H3
E)   None of the aboveF) A) and B)
G) C) and D)

Question 7

A compound with an empirical formula of C2H4Br has a molar mass of 215.90 g/mol. What is the molecular formula

Accepted Answer

A)   C4H8Br2
B)   C2H4Br
C)   CHBr
D)   C6H12Br3
E)   C4H8BrF) A) and D)
G) C) and E)

Question 8

A mass spectrometer works by ionizing atoms or molecules, and then accelerating them through oppositely charged plates. The mass is obtained by

Accepted Answer

A)   measuring the force of impact on a detecting screen, and then calculating the mass using force = mass * acceleration.
B)   suspending the ions in an applied electric field, and then calculating mass by the setting the downward gravitational force equal to the upward electrostatic force.
C)   measuring the magnitude of deflection as the ions pass through a magnetic field to obtain the charge-to-mass ratio, and then calculating the mass from that ratio.
D)   measuring the time it takes for the ions to hit the detector at a known distance to calculate the acceleration, and then calculating mass from force = mass * acceleration.E) A) and B)
F) B) and C)

Question 9

How many moles of C are in 1.22 moles of C6H12O6

Accepted Answer

A)   7.32 moles C
B)   87.9 moles C
C)   1.22 moles C
D)   14.7 moles C
E)   2.44 moles CF) B) and E)
G) B) and D)

Question 10

What is the mass of 3.00 moles of ethanol, C2H6O

Accepted Answer

A)   4.99 * 10-24 g
B)   138 g
C)   6.52 * 10-2 g
D)   50.0 g
E)   1.81 * 1024 gF) D) and E)
G) A) and D)

Question 11

Oxidation of a hydrocarbon gave a product composed of carbon, hydrogen, and oxygen. The product that was purified and sent off for elemental analysis giving the following mass percents: 68.85% C and 4.95% H. Determine the empirical formula of this compound.

Accepted Answer

A)   C6H6O5
B)   C7H8O3
C)   C4H6O6
D)   C7H6O2
E)   None of the aboveF) A) and C)
G) A) and B)

Question 12

What is the theoretical yield of PI3 if 48.0 g of I2 are reacted with an excess of phosphorus according to the following chemical equation?
2P(s)  + 3I2(s)   →\rarr→  2PI3(s)

Accepted Answer

A)   51.9 g
B)   51.7 g
C)   51.5 g
D)   51.4 g
E)   None of the above F) A) and D)
G) D) and E)

Question 13

Boron obtained from borax deposits in Death Valley consists of two isotopes. They are boron-10 and boron-11 with atomic masses of 10.013 amu and 11.009 amu, respectively. The atomic mass of boron is 10.81 amu (see periodic table) . Which isotope of boron is more abundant, boron-10 or boron-11

Accepted Answer

A)   Cannot be determined from data given
B)   Neither, their abundances are the same.
C)   Boron-10
D)   Boron-11E) All of the above
F) A) and B)

Question 14

Calculate the molar mass of (NH4) 2SO4.

Accepted Answer

A)   114.11 g/mol
B)   228.22 g/mol
C)   118.14 g/mol
D)   63.09 g/mol
E)   132.15 g/molF) A) and C)
G) A) and B)

Question 15

What percent by mass of oxygen is present in carbon monoxide, CO

Accepted Answer

A)   57%
B)   58%
C)   59 %
D)   60. %
E)   None of the aboveF) C) and D)
G) A) and E)

Question 16

Ammonia reacts with oxygen to form nitric oxide and water vapor: 4NH3 + 5O2  →\rarr→  4NO + 6H2O
What is the theoretical yield of water, in moles, when 40.0 g NH3 and 50.0 g O2 are mixed and allowed to react

Accepted Answer

A)   1.30 mol
B)   1.57 mol
C)   1.87 mol
D)   3.53 mol
E)   None of these. F) All of the above
G) A) and B)

Question 17

Liquid heptane, C7H16, burns in oxygen gas to yield carbon dioxide and water. What mass of water is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Accepted Answer

A)   1.85 g
B)   2.70 g
C)   14.8 g
D)   21.6 g
E)   31.6 gF) A) and B)
G) A) and C)

Question 18

Hydrogen gas is reacted with nitrogen gas to form ammonia gas. Write the balanced reaction (omit state symbols (s) , (l) , (g) , (aq) , etc.) .

Accepted Answer

A)   3H2 + 2N2  →\rarr→   2NH3
B)   2H2 + N2  →\rarr→  2NH3
C)   3H2 + N2  →\rarr→  2NH3
D)   2H2 + N2  →\rarr→ 3NH3
E)   None of the above are balanced F) None of the above
G) A) and D)

Question 19

Calculate the mass of 4.50 moles of chlorine gas, Cl2.

Accepted Answer

A)   6.34 * 10-2 g
B)   4.50 g
C)   15.7 g
D)   160. g
E)   319 gF) A) and D)
G) B) and D)

Question 20

Phosgene, a poisonous gas used during WWI, is composed of 12.1% C, 16.2% O, and 71.1% Cl. What is the empirical formula of phosgene

Accepted Answer

A)   CO2Cl
B)   C3O Cl2
C)   C2O3Cl3
D)   COCl2
E)   None of the aboveF) A) and D)
G) A) and C)

Exam 3: Mass Relationships in Chemical Reactions

Oxidation of a hydrocarbon gave a product composed of carbon, hydrogen, and oxygen. The product that was purified and sent off for elemental analysis giving the following mass percents: 68.85% C and 4.95% H. Determine the empirical formula of this compound.

Correct Answer
verified

When a 0.860 g sample of an organic compound containing C, H, and O was burned completely in oxygen, 1.64 g of CO₂ and 1.01 g of H₂O were produced. What is the empirical formula of the compound

Correct Answer
verified

Boron obtained from borax deposits in Death Valley consists of two isotopes. They are boron-10 and boron-11 with atomic masses of 10.013 amu and 11.009 amu, respectively. The atomic mass of boron is 10.81 amu (see periodic table) . Which isotope of boron is more abundant, boron-10 or boron-11

Correct Answer
verified

Ammonia reacts with oxygen to form nitric oxide and water vapor: 4NH₃ + 5O₂ $\rarr$ 4NO + 6H₂O What is the theoretical yield of water, in moles, when 40.0 g NH₃ and 50.0 g O₂ are mixed and allowed to react

Correct Answer
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Correct Answer
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A compound with an empirical formula of C₂H₄Br has a molar mass of 215.90 g/mol. What is the molecular formula

Correct Answer
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What is the theoretical yield of PI₃ if 48.0 g of I₂ are reacted with an excess of phosphorus according to the following chemical equation? 2P(s) + 3I₂(s) $\rarr$ 2PI₃(s)

Correct Answer
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What is the mass of 3.50 x 10²⁴ Ti atoms

Correct Answer
verified

Determine the number of moles of aluminum in 96.7 g of Al.

Correct Answer
verified

Calculate the molar mass of (NH₄) ₂SO₄.

Correct Answer
verified

Liquid heptane, C₇H₁₆, burns in oxygen gas to yield carbon dioxide and water. What mass of water is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Correct Answer
verified

A compound with a percent composition by mass of 87.5% N and 12.5% H was recently discovered. What is the empirical formula for this compound

Correct Answer
verified

Phosgene, a poisonous gas used during WWI, is composed of 12.1% C, 16.2% O, and 71.1% Cl. What is the empirical formula of phosgene

Correct Answer
verified

Hydrogen gas is reacted with nitrogen gas to form ammonia gas. Write the balanced reaction (omit state symbols (s) , (l) , (g) , (aq) , etc.) .

Correct Answer
verified

A mass spectrometer works by ionizing atoms or molecules, and then accelerating them through oppositely charged plates. The mass is obtained by

Correct Answer
verified

What percent by mass of oxygen is present in carbon monoxide, CO

Correct Answer
verified

Calculate the mass of 4.50 moles of chlorine gas, Cl₂.

Correct Answer
verified

What is the mass of 3.00 moles of ethanol, C₂H₆O

Correct Answer
verified

Acetylene gas, HCCH(g) , can be generated in the laboratory by adding calcium carbide to excess water, as shown in the following reaction CaC₂(s) + H₂O(l) $\rarr$ HCCH(g) + CaO(s) How many grams of CaC₂ would be required to generate 0.20 moles of HCCH(g)

Correct Answer
verified

How many moles of C are in 1.22 moles of C₆H₁₂O₆

Correct Answer
verified

Exam 3: Mass Relationships in Chemical Reactions

Oxidation of a hydrocarbon gave a product composed of carbon, hydrogen, and oxygen. The product that was purified and sent off for elemental analysis giving the following mass percents: 68.85% C and 4.95% H. Determine the empirical formula of this compound.

Correct AnswerverifiedShow Answer

When a 0.860 g sample of an organic compound containing C, H, and O was burned completely in oxygen, 1.64 g of CO2 and 1.01 g of H2O were produced. What is the empirical formula of the compound

Correct AnswerverifiedShow Answer

Boron obtained from borax deposits in Death Valley consists of two isotopes. They are boron-10 and boron-11 with atomic masses of 10.013 amu and 11.009 amu, respectively. The atomic mass of boron is 10.81 amu (see periodic table) . Which isotope of boron is more abundant, boron-10 or boron-11

Correct AnswerverifiedShow Answer

Ammonia reacts with oxygen to form nitric oxide and water vapor: 4NH3 + 5O2 →\rarr→ 4NO + 6H2O What is the theoretical yield of water, in moles, when 40.0 g NH3 and 50.0 g O2 are mixed and allowed to react

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A compound with an empirical formula of C2H4Br has a molar mass of 215.90 g/mol. What is the molecular formula

Correct AnswerverifiedShow Answer

What is the theoretical yield of PI3 if 48.0 g of I2 are reacted with an excess of phosphorus according to the following chemical equation? 2P(s) + 3I2(s) →\rarr→ 2PI3(s)

Correct AnswerverifiedShow Answer

What is the mass of 3.50 x 1024 Ti atoms

Correct AnswerverifiedShow Answer

Determine the number of moles of aluminum in 96.7 g of Al.

Correct AnswerverifiedShow Answer

Calculate the molar mass of (NH4) 2SO4.

Correct AnswerverifiedShow Answer

Liquid heptane, C7H16, burns in oxygen gas to yield carbon dioxide and water. What mass of water is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Correct AnswerverifiedShow Answer

A compound with a percent composition by mass of 87.5% N and 12.5% H was recently discovered. What is the empirical formula for this compound

Correct AnswerverifiedShow Answer

Phosgene, a poisonous gas used during WWI, is composed of 12.1% C, 16.2% O, and 71.1% Cl. What is the empirical formula of phosgene

Correct AnswerverifiedShow Answer

Hydrogen gas is reacted with nitrogen gas to form ammonia gas. Write the balanced reaction (omit state symbols (s) , (l) , (g) , (aq) , etc.) .

Correct AnswerverifiedShow Answer

A mass spectrometer works by ionizing atoms or molecules, and then accelerating them through oppositely charged plates. The mass is obtained by

Correct AnswerverifiedShow Answer

What percent by mass of oxygen is present in carbon monoxide, CO

Correct AnswerverifiedShow Answer

Calculate the mass of 4.50 moles of chlorine gas, Cl2.

Correct AnswerverifiedShow Answer

What is the mass of 3.00 moles of ethanol, C2H6O

Correct AnswerverifiedShow Answer

Acetylene gas, HCCH(g) , can be generated in the laboratory by adding calcium carbide to excess water, as shown in the following reaction CaC2(s) + H2O(l) →\rarr→ HCCH(g) + CaO(s) How many grams of CaC2 would be required to generate 0.20 moles of HCCH(g)

Correct AnswerverifiedShow Answer

How many moles of C are in 1.22 moles of C6H12O6

Correct AnswerverifiedShow Answer

Correct Answer
verified

When a 0.860 g sample of an organic compound containing C, H, and O was burned completely in oxygen, 1.64 g of CO₂ and 1.01 g of H₂O were produced. What is the empirical formula of the compound

Correct Answer
verified

Correct Answer
verified

Ammonia reacts with oxygen to form nitric oxide and water vapor: 4NH₃ + 5O₂ $\rarr$ 4NO + 6H₂O What is the theoretical yield of water, in moles, when 40.0 g NH₃ and 50.0 g O₂ are mixed and allowed to react

Correct Answer
verified

Correct Answer
verified

A compound with an empirical formula of C₂H₄Br has a molar mass of 215.90 g/mol. What is the molecular formula

Correct Answer
verified

What is the theoretical yield of PI₃ if 48.0 g of I₂ are reacted with an excess of phosphorus according to the following chemical equation? 2P(s) + 3I₂(s) $\rarr$ 2PI₃(s)

Correct Answer
verified

What is the mass of 3.50 x 10²⁴ Ti atoms

Correct Answer
verified

Correct Answer
verified

Calculate the molar mass of (NH₄) ₂SO₄.

Correct Answer
verified

Liquid heptane, C₇H₁₆, burns in oxygen gas to yield carbon dioxide and water. What mass of water is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Correct Answer
verified

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
verified

Calculate the mass of 4.50 moles of chlorine gas, Cl₂.

Correct Answer
verified

What is the mass of 3.00 moles of ethanol, C₂H₆O

Correct Answer
verified

Acetylene gas, HCCH(g) , can be generated in the laboratory by adding calcium carbide to excess water, as shown in the following reaction CaC₂(s) + H₂O(l) $\rarr$ HCCH(g) + CaO(s) How many grams of CaC₂ would be required to generate 0.20 moles of HCCH(g)

Correct Answer
verified

How many moles of C are in 1.22 moles of C₆H₁₂O₆

Correct Answer
verified