Ch03 - Testbank

Chemistry, 11e (Brown/LeMay/Brusten/Murphy)

Chapter 3: Stoichiometry: Calculations with Chemical Formulas and Equations

38) What is the empirical formula of a compound that contains 29% Na, 41% S, and 30% O by mass?

A) Na2S2O3 B) NaSO2 C) NaSO D) NaSO3 E) Na2S2O6

Answer: A Diff: 3

Page Ref: Sec. 3.5

39) What is the empirical formula of a compound that contains 49.4% K, 20.3% S, and 30.3% O by mass?

A) KSO2 B) KSO3 C) K2SO4 D) K2SO3 E) KSO4

Answer: D Diff: 3

Page Ref: Sec. 3.5

Chemistry, 11e (Brown/LeMay/Brusten/Murphy)

Chapter 3: Stoichiometry: Calculations with Chemical Formulas and Equations

40) A compound contains 40.0% C, 6.71% H, and 53.29% O by mass. The molecular weight of the compound is 60.05 amu. The molecular formula of this compound is __________.

A) C2H4O2 B) CH2O C) C2H3O4 D) C2H2O4 E) CHO2

Answer: A Diff: 3

Page Ref: Sec. 3.5

41) A compound that is composed of carbon, hydrogen, and oxygen contains 70.6% C, 5.9% H, and 23.5% O by mass. The molecular weight of the compound is 136 amu. What is the molecular formula?

A) C8H8O2 B) C8H4O C) C4H4O D) C9H12O E) C5H6O2

Answer: A Diff: 3

Page Ref: Sec. 3.5

Chemistry, 11e (Brown/LeMay/Brusten/Murphy)

Chapter 3: Stoichiometry: Calculations with Chemical Formulas and Equations 42) A compound that is composed of only carbon and hydrogen contains 85.7% C and 14.3% H by mass. What is the empirical formula of the compound?

A) CH2 B) C2H4 C) CH4 D) C4H8 E) C86H14

Answer: A Diff: 3

Page Ref: Sec. 3.5

43) A compound that is composed of only carbon and hydrogen contains 80.0% C and 20.0% H by mass. What is the empirical formula of the compound?

A) C20H60 B) C7H20 C) CH3 D) C2H6 E) CH4

Answer: C Diff: 3

Page Ref: Sec. 3.5

Chemistry, 11e (Brown/LeMay/Brusten/Murphy)

Chapter 3: Stoichiometry: Calculations with Chemical Formulas and Equations

44) A compound contains 38.7% K, 13.9% N, and 47.4% O by mass. What is the empirical formula of the compound?

A) KNO3 B) K2N2O3 C) KNO2 D) K2NO3 E) K4NO5

Answer: A Diff: 3

Page Ref: Sec. 3.5

45) A compound is composed of only C, H, and O. The combustion of a 0.519-g sample of the compound yields 1.24 g of CO2 and 0.255 g of H2O. What is the empirical formula of the compound?

A) C6H6O B) C3H3O C) CH3O D) C2H6O5 E) C2H6O2

Answer: B Diff: 4

Page Ref: Sec. 3.5