Empirical and Molecular Formula

What is the empirical formula?

• The actual number of atoms in a compound

• The simplest whole number ratio of atoms in a compound

• The mass percentage of elements in a compound

• The ratio of moles of each element in a compound

Which of the following represents a molecular formula?

• CH₂O

• C₂H₄O₂

• HO

• NH₂

The empirical formula of C₆H₁₂O₆ is:

• C₃H₆O₃

• CH₂O

• C₂H₄O₂

• CHO

A compound has an empirical formula of CH₂. If its molecular formula is C₃H₆, what is the relationship?

• Molecular formula = 3 × empirical

• Molecular formula = 2 × empirical

What is the percent composition of oxygen in CO₂?

• 72.7%

• 27.3%

• 50%

• 33.3%

Which pair has the same empirical formula?

• C₂H₄ and C₃H₆

• C₂H₆ and C₃H₈

• H₂O and H₂O₂

• NO and NO₂

A sample contains 0.2 mol C, 0.4 mol H, and 0.2 mol O. What is the empirical formula?

• CHO

• CH₂O

• C₂H₄O₂

• C₀.₂H₀.₄O₀.₂

Convert 22.65 grams S to moles. Round to 2 Decimal Places

• 0.71

• 0.70

• 1.42

• 1.41

Which of the following best describes an empirical formula?

• A formula that represents the actual number of atoms in a molecule.

• A formula that shows the simplest whole-number ratio of elements in a compound.

• A formula that includes all possible isotopes of an element.

• A formula that only applies to ionic compounds.

How does the molecular formula of a compound compare to its empirical formula?

• The molecular formula is always the same as the empirical formula.

• The molecular formula is always a multiple of the empirical formula.

• The empirical formula is always a multiple of the molecular formula.

• The empirical formula contains more information about the structure of the compound than the molecular formula.