Question 1

How many moles of CF4 are there in 171 g of CF4

Accepted Answer

A)  0.51 mol 
B)  1.94 mol 
C)  4.07 mol 
D)  88.0 mol 
E)  171 mol 
A)  0.51 mol 
B)  1.94 mol 
C)  4.07 mol 
D)  88.0 mol 
E)  171 mol

Question 2

Refer to the (unbalanced) equation CS2 + CaO $\rarr$ CO2 + CaS. How many grams of CaO are required to react completely with 38 g of CS2

Accepted Answer

A)  76 g 
B)  66 g 
C)  56 g 
D)  46 g 
E)  None of the above 
A)  76 g 
B)  66 g 
C)  56 g 
D)  46 g 
E)  None of the above

Question 3

Calculate the percent composition by mass of sodium in Na2CO3.

Accepted Answer

A)  55.4% 
B)  49.4 % 
C)  43.4 % 
D)  39.4 % 
E)  None of the above 
A)  55.4% 
B)  49.4 % 
C)  43.4 % 
D)  39.4 % 
E)  None of the above

Question 4

What is the mass of 8.25 * 1019 UF6 molecules

Accepted Answer

A)  352 g 
B)  0.0482 g 
C)  1.37 * 10-4 g 
D)  2.90 * 1022 g 
E)  8.25 * 1019 g 
A)  352 g 
B)  0.0482 g 
C)  1.37 * 10-4 g 
D)  2.90 * 1022 g 
E)  8.25 * 1019 g

Question 5

The definition of a mole is an Avogadro's number of a specific entity, such as an atom or molecule.

Accepted Answer

A) True 
 B)False

Question 6

A compound with a percent composition by mass of 24.61% C, 2.75% H, and 72.64% Cl has a molar mass of 292.82 g/mol. What is the empirical formula of the compound

Accepted Answer

A)  C3H4Cl2 
B)  C3H4Cl3 
C)  C2H6Cl3 
D)  C3H5Cl3 
E)  None of the above 
A)  C3H4Cl2 
B)  C3H4Cl3 
C)  C2H6Cl3 
D)  C3H5Cl3 
E)  None of the above

Question 7

Balance the following chemical equation: P4O10 + H2O $\rarr$ H3PO4

Accepted Answer

A)  P4O10 + 4H2O $\rarr$ 4H3PO4 
B)  P4O10 + 6H2O $\rarr$4H3PO4 
C)  P4O10 + 3H2O $\rarr$ 8H3PO4 
D)  P4O10 + H2O $\rarr$ 4H3PO4 
E)  None of the above are balanced 
A)  P4O10 + 4H2O $\rarr$ 4H3PO4 
B)  P4O10 + 6H2O $\rarr$4H3PO4 
C)  P4O10 + 3H2O $\rarr$ 8H3PO4 
D)  P4O10 + H2O $\rarr$ 4H3PO4 
E)  None of the above are balanced

Question 8

Pressurized metal gas cylinders are generally used to store commonly used gases in the laboratory. At times, it can be easier to chemically prepare occasionally used gases. For example, oxygen gas can be prepared by heating KMnO4(s) according to the following chemical reaction: 
2KMnO4(s) $\rarr$K2MnO4(s) + MnO2(s) + O2(g)
How many grams of KMnO4 would you need to produce 0.27 $\underline{\text{moles}}$ of O2, assuming 100% conversion? The molar mass of KMnO4 is 158.034 g/mol.

Accepted Answer

A)  45 g KMnO4 required 
B)  55 g KMnO4 required 
C)  65 g KMnO4 required 
D)  75 g KMnO4 required 
E)  None of the above 
A)  45 g KMnO4 required 
B)  55 g KMnO4 required 
C)  65 g KMnO4 required 
D)  75 g KMnO4 required 
E)  None of the above

Question 9

Calculate the mass of N in 2.34 g of N2H4

Accepted Answer

A)  4.68 g N 
B)  65.6 g N 
C)  28.02 g N 
D)  2.05 g N 
E)  2.34 g N 
A)  4.68 g N 
B)  65.6 g N 
C)  28.02 g N 
D)  2.05 g N 
E)  2.34 g N

Question 10

Pressurized metal gas cylinders are generally used to store commonly used gases in the laboratory. At times it can be easier to chemically prepare occasionally used gases. For example, nitrogen monoxide, NO(g), can be prepared in the lab using the following chemical reaction: 3Cu(s) + 8HNO3(aq) $\rarr$ 2NO(g) + 3Cu(NO3)2(aq) + 4H2O(l)
If 5.0 g of copper metal was added to an aqueous solution containing 2.5 moles of HNO3, how many moles of NO(g) would be produced, assuming a 100% yield

Accepted Answer

A)  0.042 mole NO 
B)  0.052 mole NO 
C)  0.062 mole NO 
D)  0.72 mole NO 
E)  None of the above 
A)  0.042 mole NO 
B)  0.052 mole NO 
C)  0.062 mole NO 
D)  0.72 mole NO 
E)  None of the above

Question 11

Chlorine gas reacts with phosphorus to produce phosphorus pentachloride. How many grams of PCl5 are produced from 3.5 g of Cl2 and excess P
5Cl2(g) + 2P(s) $\rarr$ 2PCl5(s)

Accepted Answer

A)  1.4 g 
B)  4.1 g 
C)  8.2 g 
D)  0.020 g 
E)  730 g 
A)  1.4 g 
B)  4.1 g 
C)  8.2 g 
D)  0.020 g 
E)  730 g

Question 12

A method for producing pure copper metal involves the reaction of copper(I) sulfide with oxygen gas to give copper metal and sulfur dioxide. Suppose the yield of this reaction is 87%. What mass of a copper ore consisting of 46% copper(I) sulfide must be mined in order to produce 1.0 *103 kg (1.0 metric ton) of copper metal

Accepted Answer

A)  1.3 * 103 kg 
B)  1.4 * 103 kg 
C)  1.5 * 103 kg 
D)  3.2 * 103 kg 
E)  8.0 * 103 kg 
A)  1.3 * 103 kg 
B)  1.4 * 103 kg 
C)  1.5 * 103 kg 
D)  3.2 * 103 kg 
E)  8.0 * 103 kg

Question 13

Hydrogen chloride gas can be prepared by the following reaction: 2NaCl(s) + H2SO4(aq) $\rarr$ 2HCl(g) + Na2SO4(s)
How many grams of HCl can be prepared from 2.00 mol H2SO4 and 2.56 mol NaCl

Accepted Answer

A)  7.30 g 
B)  93.3 g 
C)  146 g 
D)  150 g 
E)  196 g 
A)  7.30 g 
B)  93.3 g 
C)  146 g 
D)  150 g 
E)  196 g

Question 14

How many fluorine atoms are there in 65 g of CF4

Accepted Answer

A)  0.74 atoms 
B)  3.0 atoms 
C)  4.5 * 1023 atoms 
D)  1.8 * 1024 atoms 
E)  2.4 * 1023 atoms 
A)  0.74 atoms 
B)  3.0 atoms 
C)  4.5 * 1023 atoms 
D)  1.8 * 1024 atoms 
E)  2.4 * 1023 atoms

Question 15

What is the coefficient of O2 when the following equation is properly balanced?
___ CH3OH + ___ O2 $\rarr$ ___ CO2 + ___ H2O

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  7 
E)  none of these 
A)  1 
B)  2 
C)  3 
D)  7 
E)  none of these

Question 16

How many sulfur atoms are there in 21.0 g of Al2S3

Accepted Answer

A)  8.42 * 1022 atoms 
B)  2.53 * 1023 atoms 
C)  2.14 * 1023 atoms 
D)  6.02 * 1023 atoms 
E)  6.30 * 1026 atoms 
A)  8.42 * 1022 atoms 
B)  2.53 * 1023 atoms 
C)  2.14 * 1023 atoms 
D)  6.02 * 1023 atoms 
E)  6.30 * 1026 atoms

Question 17

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

Accepted Answer

A)  CH4 
B)  C2H4 
C)  C3H4 
D)  C2H6 
E)  C3H8 
A)  CH4 
B)  C2H4 
C)  C3H4 
D)  C2H6 
E)  C3H8

Question 18

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

Accepted Answer

A)  4.49 g 
B)  6.59 g 
C)  31.5 g 
D)  46.1 g 
E)  71.8 g 
A)  4.49 g 
B)  6.59 g 
C)  31.5 g 
D)  46.1 g 
E)  71.8 g

Question 19

What is the molecular mass of nicotine, C10H14N2

Accepted Answer

A)  27.03 amu 
B)  148.22 amu 
C)  149.13 amu 
D)  81.12 amu 
E)  162.23 amu 
A)  27.03 amu 
B)  148.22 amu 
C)  149.13 amu 
D)  81.12 amu 
E)  162.23 amu

Question 20

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

Accepted Answer

A)  C10H6O 
B)  C9H18O 
C)  C16H28O4 
D)  C20H12O2 
E)  C18H36O2 
A)  C10H6O 
B)  C9H18O 
C)  C16H28O4 
D)  C20H12O2 
E)  C18H36O2

Exam 3: Mass Relationships in Chemical Reactions

How many moles of CF4 are there in 171 g of CF4

Refer to the (unbalanced) equation CS2 + CaO →\rarr→ CO2 + CaS. How many grams of CaO are required to react completely with 38 g of CS2

Calculate the percent composition by mass of sodium in Na2CO3.

What is the mass of 8.25 * 1019 UF6 molecules

The definition of a mole is an Avogadro's number of a specific entity, such as an atom or molecule.

A compound with a percent composition by mass of 24.61% C, 2.75% H, and 72.64% Cl has a molar mass of 292.82 g/mol. What is the empirical formula of the compound

Balance the following chemical equation: P4O10 + H2O →\rarr→ H3PO4

Calculate the mass of N in 2.34 g of N2H4

Chlorine gas reacts with phosphorus to produce phosphorus pentachloride. How many grams of PCl5 are produced from 3.5 g of Cl2 and excess P 5Cl2(g) + 2P(s) →\rarr→ 2PCl5(s)

Hydrogen chloride gas can be prepared by the following reaction: 2NaCl(s) + H2SO4(aq) →\rarr→ 2HCl(g) + Na2SO4(s) How many grams of HCl can be prepared from 2.00 mol H2SO4 and 2.56 mol NaCl

How many fluorine atoms are there in 65 g of CF4

What is the coefficient of O2 when the following equation is properly balanced? ___ CH3OH + ___ O2 →\rarr→ ___ CO2 + ___ H2O

How many sulfur atoms are there in 21.0 g of Al2S3

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

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

What is the molecular mass of nicotine, C10H14N2

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

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How many moles of CF₄ are there in 171 g of CF₄

Refer to the (unbalanced) equation CS₂ + CaO $\rarr$ CO₂ + CaS. How many grams of CaO are required to react completely with 38 g of CS₂

Calculate the percent composition by mass of sodium in Na₂CO₃.

What is the mass of 8.25 * 10¹⁹ UF₆ molecules

Balance the following chemical equation: P₄O₁₀ + H₂O $\rarr$ H₃PO₄

Calculate the mass of N in 2.34 g of N₂H₄

Chlorine gas reacts with phosphorus to produce phosphorus pentachloride. How many grams of PCl₅ are produced from 3.5 g of Cl₂ and excess P 5Cl₂(g) + 2P(s) $\rarr$ 2PCl₅(s)

Hydrogen chloride gas can be prepared by the following reaction: 2NaCl(s) + H₂SO₄(aq) $\rarr$ 2HCl(g) + Na₂SO₄(s) How many grams of HCl can be prepared from 2.00 mol H₂SO₄ and 2.56 mol NaCl

How many fluorine atoms are there in 65 g of CF₄

What is the coefficient of O₂ when the following equation is properly balanced? _ CH₃OH + _ O₂ $\rarr$ _ CO₂ + _ H₂O

How many sulfur atoms are there in 21.0 g of Al₂S₃

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

What is the molecular mass of nicotine, C₁₀H₁₄N₂