Empirical Formula Continued

Multiple Choice

What is the empirical formula of a substance with the molecular formula C₂H₄?

• C₂H₂

• C₂H₂

• C₁H₁

• CH₂

Multiple Choice

What is the empirical formula of a substance with the molecular formula X₂₀Y₁₅?

• X₁₀Y₁₅

• X₅Y₃

• X₄Y₃

• X₂₀Y₁₅

Multiple Choice

What is the empirical formula of this substance?

• SO

• SO₂

• S₂O2

• SiO₂

Match

Match the terms:

• is a formula that shows the number and type of atoms are present in a compound.

• is the simplest whole-number ratio of moles of elements in the compound.
• tells the percent of each part of an element in a compound by mass

• Is used to help change volume units, mass units or number of particles

Molecular Formula

Empirical Formula

Percent composition

Molar Conversions

• Molecular Formula

• Empirical Formula

• Percent composition

• Molar Conversions

Multiple Choice

What is the Mr of CO₂?

• 16

• 12

• 32

• 44

Multiple Choice

What is the Mr of the compound Na₂SO₄?

• 142

• 140

• 71

• 172

Multiple Choice

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

• Mg₄N₃
• MgN₂
• Mg₃N₂ 
• MgN

Multiple Choice

Which of the following is considered an empirical formula?

• S₂O₄

• C₆H₁₂O₆
• H₂O
• C₂H₄

Multiple Choice

You are given the following percentages: 40.05% S and 59.95% O. Find the empirical formula for these elements.

• SO
• SO₂

• SO₃

• SO₄

Multiple Choice

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇
• C₂H₄O₂ and C₆H₁₂O₆
• C₃H₆O₃ and C₂H₆O₂
• CH₄ and C₂H₆

Multiple Choice

A formula with the lowest whole # ratio of elements in a compound is called

• Molecular Formula
• Chemical Formula
• Empirical Formula 
• Distance Formula

Multiple Choice

What is the percent composition of oxygen in carbon dioxide ( $$CO_2$$ )?

• $$\frac{\text{mass of C}}{\text{molar mass of } CO_2} \times 100$$

• $$\frac{\text{mass of O}_2}{\text{molar mass of } CO_2} \times 100$$

• $$\frac{\text{molar mass of } CO_2}{\text{mass of C}} \times 100$$

• $$\frac{\text{mass of O}}{\text{molar mass of } CO_2} \times 100$$

Multiple Choice

What is the percent by mass of fluorine in CaF₂?

(Ca = 40.08 g/mol, F = 19.00 g/mol)

• 24%
• 49%
• 51%
• 65%

Multiple Choice

If a sample has a mass of 58.5 grams and is composed of 39.3 g of Na, 18.6 g of C, and 0.6 g of H, what is the percent composition by mass of carbon?

• 31.8%

• 33.3%

• 35.7%

• 37.6%

Multiple Choice

What is the percent composition by mass of oxygen in water ( $$H_2O$$ )?

• 11%

• 89%

• 67%

• 33%

Multiple Choice

What is the percent composition by mass of oxygen in carbon dioxide ( $$CO_2$$ )?

• 27.3%

• 42.9%

• 57.1%

• 72.7%