Percent Composition, Empirical and Molecular Formula

Whats the empirical formula of a molecule containing 18.7% of Lithium, 16.3% of Carbon and 65.0% of oxygen?

• CO₂Li₃

• Li₂CO₃

• Li₃CO₂

• LiCO₅

Tags

NGSS.HS-PS1-7

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇

• C₂H₄O₂ and C₆H₁₂O₆

• C₃H₆O₃ and C₂H₆O₂

• CH₄ and C₂H₆

A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?

• Mg₄N₃

• MgN₂

• Mg₃N₂ 

• MgN

What is the molecular formula if the empirical formula is CH₂O and the molecular molar mass is 180.18?

• CH₂O

• C₂H₄O₂

• C₄H₈O₄

• C₆H₁₂O₆

• 92.3%

• 84.1%

• 77.4%

• 85.7%

• 5

• 7

• 10

• 12

Tags

NGSS.MS-PS1-1

A compound contains 40% sulfur and 60% oxygen by mass. What is the empirical formula of the compound? Assume the molar mass of sulfur (S) is 32 g/mol and oxygen (O) is 16 g/mol.

• SO

Tags

NGSS.HS-PS1-1

• 25%

• 20%

• 75%

• 14.3%

• 35.00%

• 28.13%

• 17.65%

• 22.22%

What is the empirical formula for a compound if it contains 70% iron (Fe) and 30% oxygen (O) by mass? Assume atomic masses: Fe = 56 g/mol, O = 16 g/mol.

• FeO