On Level % Composition and Empirical/Molecular Formulas

Front

What is the empirical formula?

Back

The empirical formula is the simplest whole-number ratio of the elements in a compound.

Front

How do you calculate the percentage composition of an element in a compound?

Back

To calculate the percentage composition, divide the mass of the element in one mole of the compound by the molar mass of the compound, then multiply by 100.

Front

What is the molar mass of carbon monoxide (CO)?

Back

The molar mass of CO is approximately 28.01 g/mol (12.01 g/mol for C + 16.00 g/mol for O).

Front

If a compound contains 40% sulfur and 60% oxygen, what is the empirical formula?

Back

The empirical formula is SO3.

Front

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

Back

The percentage of carbon in CO2 is approximately 27%.

Front

How do you determine the empirical formula from mass percentages?

Back

Convert the mass percentages to grams, then to moles, and find the simplest mole ratio.

Front

What is the molecular formula?

Back

The molecular formula shows the actual number of atoms of each element in a molecule of a compound.

Front

How do you find the molecular formula from the empirical formula?

Back

Multiply the subscripts in the empirical formula by a whole number to match the molar mass of the compound.

Front

What is the empirical formula of a compound containing 2.40 g of J with 0.473 g of nitrogen, 33.8% carbon, and 1.41% hydrogen?

Back

The empirical formula is C2HNO2.

Front

What is the percentage of oxygen in carbon monoxide (CO)?

Back

The percentage of oxygen in CO is approximately 57%.