Moles, Percent Composition, Empirical and Molecular Formulas

Given the following: 42.07% Na, 18.89% P, and 39.04% O, determine the empirical formula.

• NaPO₂

• Na₂PO₃

• Na₃PO₄

• NaPO₄

What is the empirical formula if you have 81.82% carbon and 18.18% hydrogen?

• C3H8

• CH4

• C2H2

• C4H10

What is the percent composition by mass of oxygen in the compound MgSO₄ (gram formula mass = 120 g/mol)?

• 20%

• 27%

• 46%

• 53%

Glycerol has a molar mass of 92.09g/mol. Its percent composition is: 39.12% C, 8.75% H, and 51.12% O. What is the molecular formula for glycerol?

• C₂H₃O₂

• CH₂O

• C₂H₄O₂

• C₃H₈O₃

• 0.5 moles

• 1 mole

• 1.11 moles

• 5.56 moles

Tags

NGSS.HS-PS1-7

Which element in the compound will have the HIGHEST percent composition?

Tags

NGSS.HS-PS1-3

NGSS.HS-PS1-7

• 35.00%

• 28.13%

• 17.65%

• 22.22%

• 25.13%

• 74.87%

• 20.11%

• 79.89%

Tags

DOK Level 2: Skill/Concept

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

• 25%

• 20%

• 75%

• 14.3%