U3 Empirical and Molecular Formulas: Mastery Test

A substance contains 36.1 percent calcium and 63.9 percent chlorine by weight. What is the empirical formula of the given compound?

• CaCl

• C8a0.5Cl1.8

• CaCl2

• Ca2Cl4

What is the molecular formula of a compound with the empirical formula CH and a molar mass of 39.01 grams per mole?

• CH

• C2H2

• C3H3

• C6H6

Select the correct answer. What is the molecular formula of a compound with the empirical formula NO₂ and a molar mass of 138.02 grams per mole?

• NO

• NO₂

• N₃O₃

• N₃O₆

Select the correct answer. What does the empirical formula of a compound describe?

• the type and number of atoms

• the type and ratio of atoms

• the number of atoms

• the type and mass of atoms

Tags

NGSS.MS-PS1-1

Select the correct answer. What is the empirical formula of a compound that contains 25.92 percent nitrogen and 74.07 percent oxygen?

• NO

• N₂O₂.₅

• N₂O₅

• NO₂

Ibuprofen, a common pain remedy, has an empirical formula of C₇H₁₀O and a molar mass of approximately 218.078 grams per mole. What is the molecular formula of ibuprofen?

• C₆H₁₁O₂

• C₁₄H₁₈O₂

• C₂₁H₂₇O₃

• C₃.₅H₄.₅O₀.₅

What is the empirical formula of a compound containing carbon, hydrogen, and oxygen in the ratio 14:42:84?

• C₁₄H₄₂O₈₄

• C₇H₂₁O₄₂

• C₂H₆O₁₂

• CH₃O₆

What is the empirical formula of a compound that contains 32.39 percent sodium, 22.53 percent sulfur, and 45.07 percent oxygen?

• NaSO

• Na2S2O3

• Na2S3O2

• Na2SO4

Tags

NGSS.HS-PS1-7

A compound contains 69.94 percent iron and 30.06 percent oxygen. What is its molecular formula if the molar mass of the compound is 199.55 grams per mole?

• Fe2O3

• Fe1.5O1

• FeO

• Fe3O2

What is the empirical formula of a compound that contains 40 percent carbon, 6.7 percent hydrogen, and 53.3 percent oxygen by mass?

• CH2O

• C2H4O3

• C6H16O6

• CHO