Deck 4: Chemical Composition

Question 1

A 6.25 g sample of magnetite (Fe₃O₄)contains 4.52 g of Fe. What are the percentages of iron and oxygen in magnetite?

A)28.6% Fe and 71.4% O
B)42.8% Fe and 57.2% O
C)72.3% Fe and 27.7% O
D)27.7% Fe and 72.3% O
E)57.2% Fe and 42.8% O

Answer 1

72.3% Fe and 27.7% O

Question 2

Which of the following statements is incorrect?

A)H₂SO₃ has 1.5 times as many oxygen atoms as hydrogen atoms.
B)Fe₂(SO₄)₃ has six times as many oxygen atoms as iron ions.
C)N₂H₄ has twice as many hydrogen atoms as nitrogen atoms.
D)MgF₂ has half as many fluoride ions as magnesium ions.
E)Carbon dioxide has twice as many oxygen atoms as carbon atoms.

Answer 2

MgF₂ has half as many fluoride ions as magnesium ions.

Question 3

Which of the following statements is incorrect?

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.

Answer 3

N₂H₄ has four times as many hydrogen atoms as nitrogen atoms.

Question 4

How many carbon atoms are there in 0.50 mole of CO₂?

A)0.50
B)1.50
C)3.0 × 10²³
D)9.0 × 10²³
E)8.3 × 10²⁵

Question 5

How many molecules of HCl are present in 0.250 mol of HCl?

A)4.15 × 10⁻²⁵ molecules
B)1.51 × 10²³ molecules
C)2.41 × 10²⁴ molecules
D)9.11 molecules
E)0.250 molecules

Question 6

How many molecules of CO₂ are present in 0.100 mol of CO₂?

A)6.02 × 10²² molecules
B)4.40 molecules
C)1.66 × 10⁻²⁵ molecules
D)6.02 × 10²⁴ molecules
E)0.100 molecules

Question 7

Which of the following statements is incorrect?

A)CH₄ has ¼ as many carbon atoms as hydrogen atoms.
B)H₂O has twice as many oxygen atoms as hydrogen atoms.
C)SO₃ has three times as many oxygen atoms as sulfur atoms.
D)P₄O₁₀ has 2.5 times as many oxygen atoms as phosphorus atoms.
E)SrF₂ has twice as many fluoride ions as strontium ions.

Question 8

How many formula units are in 2.0 moles of Fe(NO₃)₂?

A)1.2 × 10²⁴
B)3.6 × 10²⁴
C)1.1 × 10²⁵
D)2.0
E)18

Question 9

How many formula units are there in 2.5 moles of MgCl₂?

A)2.5
B)7.5
C)1.5 × 10²⁴
D)4.5 × 10²⁴
E)4.2 × 10⁻²⁴

Question 10

How many formula units are in 0.25 mole of Na₂O?

A)4.5 × 10²³
B)0.75
C)1.5 × 10²³
D)4.2 × 10⁻²⁵
E)0.25

Question 11

How many nitrate ions are present in 0.200 mol of Zn(NO₃)₂?

A)1.20 × 10²³ NO₃⁻ ions
B)2.41 × 10²³ NO₃⁻ ions
C)3.01 × 10²⁴ NO₃⁻ ions
D)6.64 × 10⁻²⁵ NO₃⁻ ions
E)0.400 NO₃⁻ ions

Question 12

How many oxygen atoms are there in 0.25 mole of CO₂?

A)0.50
B)0.25
C)3.0 × 10²³
D)1.5 × 10²³
E)4.2 × 10⁻²⁵

Question 13

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

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

Question 14

A 7.50 g sample of pyrite (FeS₂)contains 3.49 g of iron. What are the percentages of iron and sulfur in pyrite (also known as "Fool's Gold" because of its golden color)?

A)57.4% Fe and 42.6% S
B)66.7% Fe and 33.3% S
C)33.3% Fe and 66.7% S
D)46.5% Fe and 53.5% S
E)53.5% Fe and 46.5% S

Question 15

Which of the following statements is incorrect?

A)PH₃ has 3 times as many hydrogen atoms as phosphorus atoms.
B)MgO has an equal number of magnesium ions and oxygen ions.
C)BaBr₂ has half as many barium ions as bromide ions.
D)N₂O₅ has 2.5 times as many nitrogen atoms as oxygen atoms.
E)SF₄ has 4 times as many fluorine atoms as sulfur atoms.

Question 16

Malachite is a green colored mineral that is 57.5% copper. What mass of copper is present in a 250.0 g sample of malachite?

A)63.6 g
B)127 g
C)435 g
D)36.5 g
E)144 g

Question 17

Barium sulfate is a compound used to assist in diagnosing medical problems through x-ray analysis and is 58.8% barium. What mass of barium is present in a 620 mg tablet of barium sulfate?

A)81 mg
B)230 mg
C)360 mg
D)1100 mg
E)11 mg

Question 18

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

A)H₂SO₃, SCl₅, C₂H₅
B)H₂SO₄, SCl₅, C₂H₅
C)H₂SO₄, SCl₆, C₂H₆
D)H₂SO₄, SCl₆, CH₆
E)H₂SO₃, SCl₆, C₂H₆

Question 19

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

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 20

A 5.05 g sample of quartz (SiO₂)contains 2.36 g of silicon. What are the percentages of silicon and oxygen in quartz?

A)53.3% Si and 46.7% O
B)46.7% Si and 53.3% O
C)29.9% Si and 70.1% O
D)70.1% Si and 29.9% O
E)46.7% Si, and insufficient information to calculate % O

Question 21

If 4.05 × 10²³ molecules of a substance have a mass of 86.2 g, what is the molar mass of the substance?

A)128 g/mol
B)3.49 × 10²⁵ g/mol
C)2.13 × 10²² g/mol
D)4.70 × 10²¹ g/mol
E)58.0 g/mol

Question 22

How many hydrogen atoms are there in 2.0 moles of CH₄?

A)8.0
B)2.0
C)1.2 × 10²⁴
D)1.3 × 10⁻²³
E)4.8 × 10²⁴

Question 23

If 8.53 × 10²⁴ molecules of a substance have a mass of 483 g, what is the molar mass of the substance?

A)6.86 × 10³ g/mol
B)34.1 g/mol
C)4.12 × 10²⁷ g/mol
D)1.77 × 10²² g/mol
E)0.0293 g/mol

Question 24

Rank the following in order of increasing mass: 1.0 mole of SF₄, 0.50 mole of H₂S, 0.20 mole of Cu, and 0.10 mole of Pb.

A)Pb < Cu < H₂S < SF₄
B)Cu < H₂S < Pb < SF₄
C)Pb < Cu < SF₄ < H₂S
D)Cu < H₂S < SF₄ < Pb
E)SF₄ < H₂S < Cu < Pb

Question 25

Calculate the molar mass of HCl.

A)36.46 g/mol
B)13.02 g/mol
C)2.196 × 10²⁵ g/mol
D)6.054 × 10^-23 g/mol
E)72.92 g/mol

Question 26

Which of the following statements regarding atoms, molecules, and moles is correct?

A)Chemists are inherently lazy, so they weigh substances in order to avoid counting out the atoms or molecules in a sample.
B)It would be possible for an individual to count out a mole of atoms or molecules if they had a few days to do it.
C)A single grain of sand has about as many formula units of SiO₂ as there are sand grains on all of the beaches on Earth.
D)A mole of HCl would have the same mass as a mole of NaCl, since they have the same number of particles.
E)Since a mole of LiCl has a mass of 42.39 g, the average mass of a LiCl formula unit would be 42.39 mole.

Question 27

Calculate the molar mass of PH₃.

A)40.11 g/mol
B)31.98 g/mol
C)33.99 g/mol
D)93.92 g/mol
E)2.05 × 10²⁵ g/mol

Question 28

Rank the following in order of increasing mass: 1.0 mole of methane (CH₄), 0.50 mole of water (H₂O), 0.20 mole of Fe, and 0.010 mole of U.

A)U < Fe < H₂O < CH₄
B)H₂O < CH₄ < Fe < U
C)H₂O < CH₄ < U < Fe
D)U < H₂O < CH₄ < Fe
E)U < H₂O < Fe < CH₄

Question 29

Calcium phosphate, Ca₃(PO₄)₂, is used to treat calcium deficiencies. What is the molar mass of this compound?

A)87.05 g/mol
B)167.05 g/mol
C)279.21 g/mol
D)230.02 g/mol
E)310.18 g/mol

Question 30

How many nitrogen atoms are present in 0.150 mol of Zn(NO₃)₂?

A)9.03 × 10²² atoms
B)1.81 × 10²³ atoms
C)4.98 × 10⁻²⁵ atoms
D)0.300 atoms
E)0.450 atoms

Question 31

Calculate the molar mass of Na₂SO₄.

A)94.05 g/mol
B)71.06 g/mol
C)119.06 g/mol
D)142.04 g/mol
E)110.05 g/mol

Question 32

How many oxygen atoms are present in 1.50 mol of Zn(NO₃)₂?

A)4.50 atoms
B)9.00 atoms
C)9.03 × 10²³ atoms
D)5.42 × 10²⁴ atoms
E)1.49 × 10⁻²³ atoms

Question 33

Calculate the molar mass of CuSO₄•5H₂O.

A)159.62 g/mol
B)249.69 g/mol
C)177.64 g/mol
D)185.72 g/mol
E)446.48 g/mol

Question 34

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.

A)SO₃ < SO₂ < Rn < Mo
B)SO₂ < SO₃ < Mo < Rn
C)Mo < Rn < SO₃ < SO₂
D)Mo < Rn < SO₂ < SO₃
E)Rn < Mo < SO₃ < SO₂

Question 35

Calculate the molar mass of Fe₃(PO₄)₂.

A)237.64 g/mol
B)262.52 g/mol
C)245.79 g/mol
D)357.49 g/mol
E)525.04 g/mol

Question 36

Calculate the molar mass of C₃H₆Cl₂.

A)155.08 g/mol
B)77.54 g/mol
C)48.47 g/mol
D)72.49 g/mol
E)112.98 g/mol

Question 37

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

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 38

Rank the substances in the figure from least atoms per mole to most atoms per mole.

A)SiO₂ < C₂H₆ < CO₂ < Fe
B)C₂H₆ < SiO₂ = CO₂ < Fe
C)Fe < CO₂ = SiO₂ < C₂H₆
D)Fe < CO₂ < SiO₂ < C₂H₆
E)C₂H₆ < SiO2 < CO₂ < Fe

Question 39

If 7.50 × 10²⁴ molecules of a substance have a mass of 454 g, what is the molar mass of the substance?

A)2.73 × 10²⁶ g/mol
B)3.41 × 10²⁷ g/mol
C)5.65 × 10³ g/mol
D)36.5 g/mol
E)12.5 g/mol

Question 40

Rank the substances in the figure from least atoms per mole to most atoms per mole.

A)SO₃ < H₂SO₄ < NaCl < Na
B)Na < NaCl < SO₃ < H₂SO₄
C)Na < NaCl < H₂SO₄ < SO₃
D)NaCl < Na < SO₃ < H₂SO₄
E)H₂SO₄ < SO₃ < NaCl < Na

Question 41

Rank the following elements in order from least to most number of moles of atoms in a 10.0 g sample: Sn, Si, Se, S

A)Sn < Se < S < Si
B)Si < S < Se < Sn
C)Si < S < Sn < Se
D)S < Si < Se < Sn
E)Se < Sn < S < Si

Question 42

If the molar mass of a substance is 20.0 g/mol, what is the mass of 4.01 × 10²³ molecules of the substance?

A)30.0 g
B)13.3 g
C)8.02 × 10²⁴ g
D)1.20 × 10²⁵ g
E)3.00 g

Question 43

If the molar mass of a substance is 20.0 g/mol, what is the mass of 3.01 × 10²⁵ molecules of the substance?

A)0.400 g
B)10.0 g
C)1.00 × 10³ g
D)6.02 × 10²⁶ g
E)1.20 × 10²⁵ g

Question 44

Rank the following elements in order from least to most number of moles of atoms in a 10.0 g sample: Li, He, Mg, C

A)He < C < Li < Mg
B)C < Li < Mg < He
C)Li < C < Mg < He
D)He < Li < C < Mg
E)Mg < C < Li < He

Question 45

A 50.0 g sample of a compound contains 2.20 × 10²³ molecules. Which of the following could be this compound?

A)PH₃
B)NH₃
C)PCl₃
D)PCl₅
E)NF₃

Question 46

A chemical reaction produces 7.25 moles of barium sulfate, BaSO₄. What mass of barium sulfate is produced?

A)185 g
B)233 g
C)1.69 × 10³ g
D)31.1 g
E)3.11 × 10^-2 g

Question 47

A 100.0 g sample of a compound contains 1.37 × 10²⁴ molecules. Which of the following could be this compound?

A)CO₂
B)NH₃
C)CH₄
D)CCl₄
E)CF₄

Question 48

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

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

Question 49

If the molar mass of a substance is 34.1 g/mol, what is the mass of 3.01 × 10²⁴ molecules of the substance?

A)17.1 g
B)6.82 g
C)8.83 × 10²² g
D)1.03 × 10²⁴ g
E)1.70 × 10² g

Question 50

A chemical reaction requires 3.50 moles of copper(II)nitrate, Cu(NO₃)₂. What mass of copper(II)nitrate is needed?

A)327 g
B)93.6 g
C)188 g
D)656 g
E)53.6 g

Question 51

If you have 10.0 g of sodium chloride, NaCl, how many formula units are in the sodium chloride sample?

A)2.84 × 10²⁵
B)3.52 × 10²⁴
C)6.02 × 10²⁴
D)1.03 × 10²³
E)0.171

Question 52

5.06 moles of iron(II)phosphate, Fe₃(PO₄)₂, are produced in a reaction. What mass of iron(II)phosphate is produced?

A)5.20 × 10² g
B)20.3 g
C)1.81 × 10³ g
D)3.05 × 10²⁴ g
E)70.7 g

Question 53

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

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

Question 54

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

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

Question 55

Calculate the number of moles of NaOH (sodium hydroxide, an ingredient in drain cleaners and oven cleaners)in a 10.0 g sample of this substance.

A)1.51 × 10²³ moles
B)1.66 × 10²³ mole
C)0.208 mole
D)4.00 × 10² moles
E)0.250 mole

Question 56

A chemical reaction requires 6.00 moles of Fe(NO₃)₃. What mass of iron(III)nitrate is needed?

A)24.3 g
B)875 g
C)40.3 g
D)1.45 × 10³ g
E)515 g

Question 57

Calculate the moles of sucrose, C₁₂H₂₂O₁₁, in a 15.0-g sample of this substance.

A)342 mol
B)22.8 mol
C)5.13 × 10³ mol
D)4.38 × 10^-2 mol
E)0.517 mol

Question 58

If the molar mass of a substance is 44.01 g/mol, what is the mass of 1.05 × 10²⁴ molecules of the substance?

A)76.7 g
B)1.74 g
C)4.62 × 10²⁵ g
D)4.19 × 10^-23 g
E)25.2 g

Question 59

How many molecules are in a sample of sucrose (sugar), C₁₂H₂₂O₁₁ that has a mass of 15.0 g?

A)0.0438
B)2.64 × 10²²
C)0.0824
D)4.96 × 10²²
E)9.03 × 10²⁴

Question 60

Calculate the number of moles of CaCO₃ (calcium carbonate, or limestone)in a 20.0 g sample of this substance.

A)2.00 × 10³ moles
B)0.200 mole
C)0.294 mole
D)1.36 × 10³ moles
E)1.20 × 10³ moles

Question 61

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

A)N₂ < N₂O₅ < NH₃ < NH₄Cl
B)N₂O₅ < NH₄Cl < NH₃ < N₂
C)N₂ < NH₃ < NH₄Cl < N₂O₅
D)NH₃ < NH₄Cl < N₂ < N₂O₅
E)NH₄Cl < NH₃ < N₂ < N₂O₅

Question 62

How many formula units are in a sample of NaCl that has a mass of 175 g?

A)2.01 × 10²³ formula units
B)1.80 × 10²⁴ formula units
C)6.16 × 10²⁷ formula units
D)1.05 × 10²⁶ formula units
E)2.91 × 10^-22 formula units

Question 63

Rank the following compounds in order from least phosphorus atoms to most phosphorus atoms in a 50.0 g sample: P₄, P₄O₁₀, PH₃, PCl₃

A)PCl₃ < P₄O₁₀ < PH₃ < P₄
B)PCl₃ < P₄O₁₀ < P₄ < PH₃
C)P₄ < PH₃ < P₄O₁₀ < PCl₃
D)P₄O₁₀ < PCl₃ < PH₃ < P₄
E)P₄ < P₄O₁₀ < PCl₃ < PH₃

Question 64

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

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 65

How many moles are in a sample of ethanol, CH₃CH₂OH that has a volume of 100.0 mL? The molar mass and density of ethanol are 46.07 g/mol and 0.789 g/mL, respectively.

A)78.9 mol
B)1.71 mol
C)36.3 mol
D)2.75 mol
E)0.504 mol

Question 66

What is the mass of 1.2 × 10²⁴ molecules of F₂?

A)0.052 g
B)9.5 g
C)19 g
D)38 g
E)76 g

Question 67

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

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

Question 68

How many molecules are in a sample of water, H₂O, which has a mass of 50.0 g?

A)1.67 × 10²⁴ molecules
B)5.42 × 10²⁶ molecules
C)2.16 × 10²³ molecules
D)3.01 × 10²⁵ molecules
E)8.30 × 10^-23 molecules

Question 69

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

A)The compounds NO₂ and N₂O₄ have the same empirical formula.
B)The compounds NO₂ and N₂O₄ have the same molecular formula.
C)The empirical formula of H₂O₂ is H₂O.
D)The empirical formula of N₂O₅ is NO_2.5.
E)The compounds PCl₃ and PCl₅ would have the same percent composition.

Question 70

How many sodium ions are in 125 g of Na₂SO₄?

A)1.06 × 0²⁴ atoms
B)5.30 × 10²³ atoms
C)6.84 × 10²³ atoms
D)1.37 × 10²⁴ atoms
E)1.46 × 10^-24 atoms

Question 71

Rank the following compounds in order from least chlorine atoms to most chlorine atoms in a 50.0 g sample: Cl₂, ClF₃, Cl₂O, PCl₃

A)ClF₃ < Cl₂O < Cl₂ < PCl₃
B)PCl₃ < Cl₂O < Cl₂ < ClF₃
C)ClF₃ < PCl₃ < Cl₂O < Cl₂
D)ClF₃ < PCl₃ < Cl₂ < Cl₂O
E)Cl₂O < Cl₂ < ClF₃ < PCl₃

Question 72

What is the mass of 3.5 × 10²³ molecules of CO₂?

A)1.7 g
B)26 g
C)0.58 g
D)75 g
E)1.5 × 10²⁵ g

Question 73

How many hydrogen atoms are in 135 g of H₂O?

A)170 atoms
B)4.51 × 10²⁴ atoms
C)9.02 × 10²⁴ atoms
D)8.04 × 10²² atoms
E)2.49 × 10^-23 atoms

Question 74

How many nitrate ions are in 75.0 g of Zn(NO₃)₂?

A)0.396 atoms
B)0.792 atoms
C)2.38 × 10²³ atoms
D)4.77 × 10²³ atoms
E)6.57 × 10^-25 atoms

Question 75

How many oxygen atoms are in 75.0 g of SO₃?

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

Question 76

How many formula units are in a sample of rust, Fe₂O₃ that has a mass of 5.0 g?

A)1.9 × 10²⁵
B)0.031
C)1.9 × 10²²
D)0.070
E)4.2 × 10²²

Question 77

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

A)The empirical formula and molecular formula of a given compound are always the same.
B)Two compounds having different percent compositions of the same two elements are not the same compound.
C)The empirical formula and molecular formula of a given compound are never the same.
D)Data on the percent composition of the elements in a given compound is insufficient to determine the empirical formula of the compound.
E)The compound S₂Cl₂ would have the same empirical and molecular formulas.

Question 78

How many moles are in a sample of ethylene glycol (commonly found in antifreeze), HOCH₂CH₂OH, that has a volume of 250.0 mL? The molar mass and density of ethylene glycol are 62.07 g/mol and 1.11 g/mL, respectively.

A)4.47 mol
B)0.276 mol
C)3.63 mol
D)1.40 × 10⁴ mol
E)1.72 × 10⁴ mol

Question 79

What is the mass of 4.5 × 10²³ molecules of SO₂?

A)2.9 × 10²⁵ g
B)64 g
C)86 g
D)36 g
E)48 g

Question 80

What is the mass of 7.4 × 10²⁴ molecules of SO₃?

A)12 g
B)590 g
C)980 g
D)6.5 g
E)0.15 g