Percent Composition & Empirical Formulas Practice

Front

What is an empirical formula?

Back

An empirical formula is the simplest whole-number ratio of atoms of each element in a compound.

Front

Which of the following is an empirical formula? CH₃COOH, C₆H₁₂O₆, H₂O

Back

H₂O is the empirical formula.

Front

How do you calculate percent composition?

Back

Percent composition is calculated by dividing the mass of each element in a compound by the total molar mass of the compound and multiplying by 100.

Front

Find the percent composition of Cu₂S. What are the percentages of Cu and S?

Back

%Cu = 79.854%, %S = 20.145%.

Front

What is the percentage of oxygen in carbon dioxide (CO₂)?

Back

72.7%.

Front

Given 40.05% S and 59.95% O, what is the empirical formula?

Back

The empirical formula is SO₃.

Front

What is the molar mass of water (H₂O)?

Back

The molar mass of water is approximately 18.02 g/mol.

Front

How do you determine the empirical formula from percent composition?

Back

Convert the percentages to grams, then to moles, and simplify the mole ratio to the smallest whole numbers.

Front

What is the empirical formula for C₆H₁₂O₆?

Back

The empirical formula is CH₂O.

Front

What is the significance of empirical formulas in chemistry?

Back

Empirical formulas provide a simple representation of the composition of a compound, which is useful for understanding its properties.