Question 1

What is the mass of 2.4 × 1023 molecules of NO2?

Accepted Answer

A)  75 g
B)  18 g
C)  1.2 × 102 g
D)  1.1 × 1023 g
E)  12 g

Question 2

The substance in the figure with the most atoms per mole is NaCl.

Accepted Answer

A) True 
 B)False

Question 3

Rank the following elements in order from least to most number of moles of atoms in a 10.0 g sample: Br, Fe, Pb, Hg

Accepted Answer

A)  Br 
B)  Pb 
C)  Fe 
D)  Br 
E)  Hg < Pb < Br < Fe

Question 4

How many chloride ions are present in 0.100 mol of MgCl2?

Accepted Answer

A)  0.200 Cl− ions
B)  6.02 × 1022 Cl− ions
C)  1.20 × 1023 Cl− ions
D)  3.32 × 10−25 Cl− ions
E)  3.01 × 1024 Cl− ions

Question 5

Calculate the number of moles of NaHCO3 (sodium bicarbonate, or baking soda) in a 5.0 g sample of this substance.

Accepted Answer

A)  0.096 mole
B)  0.060 mole
C)  420 moles
D)  3.6 × 1022 moles
E)  2.8 × 1023 mole

Question 6

Rank the following compounds in order from least nitrogen atoms to most nitrogen atoms in a 50.0 g sample: N2, N2O5, NH3, NH4Cl

Accepted Answer

A)  N2 2O5 3 4Cl
B)  N2O5 4Cl 3 2
C)  N2 3 4Cl 2O5
D)  NH3 4Cl 2 2O5
E)  NH4Cl 3 2 2O5

Question 7

How much water must be added to 500.0 mL of a 3.00 M HCl solution to obtain a solution that is 2.00 M?

Accepted Answer

A)  1.00 L
B)  1.50 L
C)  7.50 × 102 mL
D)  2.50 × 102 mL
E)  12.0 L

Question 8

The formula for novocain, a local anesthetic, is C13H21N2O2. What is the molar mass of this compound?

Accepted Answer

A)  43.03 g/mol
B)  237.32 g/mol
C)  2035.27 g/mol
D)  38.00 g/mol
E)  4.214 × 10-5 g/mol

Question 9

Calculate the molarity of a solution consisting of 75.0 g of KOH in 2.00 L of solution.

Accepted Answer

A)  37.5 M
B)  0.938 M
C)  1.34 M
D)  0.668 M
E)  2.10 × 103 M

Question 10

Rank the following in order of increasing mass: 2.0 mole of SO2, 1.0 mole of SO3, 0.50 mole of Mo, and 0.25 mole of Rn.

Accepted Answer

A)  SO3 2 
B)  SO2 3 
C)  Mo 3 2
D)  Mo 2 3
E)  Rn 3 2

Question 11

Given the following molecular formulas, determine the empirical formula of each compound: N2O5, PCl3, H2O2, C6H4Cl2.

Accepted Answer

A)  N2O5, PCl3, HO, C6H4Cl2
B)  N2O5, PCl3, H2O, C6H4Cl2
C)  N2O5, PCl3, H2O2, C3H2Cl2
D)  NO2.5, PCl3, HO, C3H2Cl
E)  N2O5, PCl3, HO, C3H2Cl

Question 12

How much water had to be added to 50.0 mL of the first solution to obtain the second solution?

Accepted Answer

A)  10.0 mL
B)  33.3 mL
C)  50.0 mL
D)  83.3 mL
E)  100.0 mL

Question 13

Which of the following sets of formulas is correct for the molecules in the figure? 2SO3, SCl4, C2H4 B) H2SO3, SCl3, C2H4 C) H2SO4, SCl3, C2H4 D) H2SO4, SCl4, CH4 E) H2SO4, SCl4, C2H4" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  H2SO3, SCl4, C2H4
B)  H2SO3, SCl3, C2H4
C)  H2SO4, SCl3, C2H4
D)  H2SO4, SCl4, CH4
E)  H2SO4, SCl4, C2H4

Question 14

Methyl butyrate is a compound that is partially responsible for the flavor of apples. It consists of 58.80% C, 9.87% H, and 31.33% O. What is the empirical formula of methyl butyrate?

Accepted Answer

A)  C6H10O3
B)  C5H10O2
C)  CH2O
D)  C4.9H9.8O1.9
E)  C4H9O2

Question 15

How many oxygen atoms are in 75.0 g of SO3?

Accepted Answer

A)  225 atoms
B)  0.937 atoms
C)  5.64 × 1023 atoms
D)  1.69 × 1024 atoms
E)  4.52 × 1025 atoms

Question 16

Calculate the moles and the mass of solute in 750.0 mL of 3.00 M NaCl.

Accepted Answer

A)  2.25 moles and 131 g
B)  2.25 moles and 0.0385 g
C)  4.00 moles and 234 g
D)  4.00 moles and 0.0684 g
E)  2.25 × 103 moles and 38.5 g

Question 17

Acetic acid is the active ingredient in vinegar. It consists of 40.00% C, 6.714% H, and 53.29% O. What is the empirical formula of acetic acid?

Accepted Answer

A)  C3.33H6.66O3.33
B)  C3H6O3
C)  CH2O
D)  C2H4O2
E)  CH3O

Question 18

Which of the following statements regarding empirical formulas, molecular formulas, and percent composition is correct?

Accepted Answer

A)  A compound with the molecular formula P4O10 would have the empirical formula P4O10.
B)  It is not possible to determine the empirical formula of a compound if given only its percent composition.
C)  If the molecular formula of a compound is C6H5Cl, its empirical formula is the same.
D)  Empirical formulas contain more information than molecular formulas.
E)  Formulas for ionic compounds are normally given as molecular formulas.

Question 19

3.00 moles of NaOH (sodium hydroxide) are needed to prepare a solution. What mass of sodium hydroxide is required?

Accepted Answer

A)  13.3 g
B)  1.20 × 102 g
C)  93 g
D)  10.3 g
E)  1.81 × 1024 g

Question 20

Which of the following statements is incorrect?

Accepted Answer

A)  N2H4 has four times as many hydrogen atoms as nitrogen atoms.
B)  SF4 has ¼ as many sulfur atoms as fluorine atoms.
C)  SO2 has twice as many oxygen atoms as sulfur atoms.
D)  Ca(NO3) 2 has six times as many oxygen atoms as calcium ions.
E)  H2SO4 has twice as many oxygen atoms as hydrogen atoms.

Exam 4: Chemical Composition

How much water had to be added to 50.0 mL of the first solution to obtain the second solution?

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3.00 moles of NaOH (sodium hydroxide) are needed to prepare a solution. What mass of sodium hydroxide is required?

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Calculate the moles and the mass of solute in 750.0 mL of 3.00 M NaCl.

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Calculate the molarity of a solution consisting of 75.0 g of KOH in 2.00 L of solution.

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The substance in the figure with the most atoms per mole is NaCl.

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Calculate the number of moles of NaHCO3 (sodium bicarbonate, or baking soda) in a 5.0 g sample of this substance.

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Rank the following compounds in order from least nitrogen atoms to most nitrogen atoms in a 50.0 g sample: N2, N2O5, NH3, NH4Cl

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How many chloride ions are present in 0.100 mol of MgCl2?

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How much water must be added to 500.0 mL of a 3.00 M HCl solution to obtain a solution that is 2.00 M?

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What is the mass of 2.4 × 1023 molecules of NO2?

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Which of the following statements regarding empirical formulas, molecular formulas, and percent composition is correct?

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Acetic acid is the active ingredient in vinegar. It consists of 40.00% C, 6.714% H, and 53.29% O. What is the empirical formula of acetic acid?

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Methyl butyrate is a compound that is partially responsible for the flavor of apples. It consists of 58.80% C, 9.87% H, and 31.33% O. What is the empirical formula of methyl butyrate?

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Which of the following statements is incorrect?

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Which of the following sets of formulas is correct for the molecules in the figure?

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How many oxygen atoms are in 75.0 g of SO3?

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Rank the following elements in order from least to most number of moles of atoms in a 10.0 g sample: Br, Fe, Pb, Hg

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Rank the following in order of increasing mass: 2.0 mole of SO2, 1.0 mole of SO3, 0.50 mole of Mo, and 0.25 mole of Rn.

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Given the following molecular formulas, determine the empirical formula of each compound: N2O5, PCl3, H2O2, C6H4Cl2.

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The formula for novocain, a local anesthetic, is C13H21N2O2. What is the molar mass of this compound?

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Calculate the number of moles of NaHCO₃ (sodium bicarbonate, or baking soda) in a 5.0 g sample of this substance.

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Rank the following compounds in order from least nitrogen atoms to most nitrogen atoms in a 50.0 g sample: N₂, N₂O₅, NH₃, NH₄Cl

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How many chloride ions are present in 0.100 mol of MgCl₂?

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What is the mass of 2.4 × 10²³ molecules of NO₂?

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How many oxygen atoms are in 75.0 g of SO₃?

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Rank the following in order of increasing mass: 2.0 mole of SO₂, 1.0 mole of SO₃, 0.50 mole of Mo, and 0.25 mole of Rn.

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Given the following molecular formulas, determine the empirical formula of each compound: N₂O₅, PCl₃, H₂O₂, C₆H₄Cl₂.

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The formula for novocain, a local anesthetic, is C₁₃H₂₁N₂O₂. What is the molar mass of this compound?

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