Mole Practice Test

What is the % composition of H in heptane, C₇H₁₆? 

What is the percent composition of carbon in a compound that contains 40.8 g carbon and 54.4 g oxygen?

Find the percent composition of potassium in a compound that contains 1.51 g of chromium, 1.13 g of potassium, and 1.62 g of oxygen.  The total mass of the sample is 4.26 g.

An empirical formula:

• is a formula that calculates the coefficients of a compound in a balanced equation.

• is the simplest whole-number ratio of moles of elements in the compound.

You are given the following percentages: 40.05% S and 59.95% O. Find the empirical formula for these elements. (keep two decimal places throughout calculations)

• SO

• SO₂

• SO₃

• SO₄

What is the empirical formula of the following molecular formula:  C₃H₆

• C₃H₆

• CH₂

• C₂H₄

• CH₃

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇

• C₂H₄O₂ and C₆H₁₂O₆

• C₃H₆O₃ and C₂H₆O₂

• CH₄ and C₂H₆

What is the empirical formula for a compound containing the following ratio:
3Na:1P:4O

• NaPO₄

• Na₃P₄O

• Na₃PO₄

• NaPO

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

• CH₂O

• C₂H₄O₂

• C₄H₈O₄

• C₆H₁₂O₆

What is the molecular formula if the empirical formula is C₂H₅ and the molecular molar mass is 58.14 g/mol?

• C₂H₅

• C₄H₁₀

• C₁H_2.5

• C₄H₈