Molecular and Empirical Formulas

Front

What is a molecular formula?

Back

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

Front

What is an empirical formula?

Back

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

Front

How do you determine the empirical formula from percent composition?

Back

1. Convert the percentage of each element to grams. 2. Convert grams to moles by dividing by the atomic mass. 3. Divide by the smallest number of moles to find the ratio.

Front

What is the empirical formula for a compound with 50% carbon and 50% hydrogen?

Back

CH

Front

If the molecular formula is C6H12O6, what is the empirical formula?

Back

CH2O

Front

What is the relationship between molecular and empirical formulas?

Back

The molecular formula is a multiple of the empirical formula.

Front

How can you find the molecular formula if you know the empirical formula and the molar mass?

Back

1. Calculate the molar mass of the empirical formula. 2. Divide the molar mass of the compound by the molar mass of the empirical formula. 3. Multiply the subscripts in the empirical formula by this ratio.

Front

What is the empirical formula for C4H8?

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C2H4

Front

What is the empirical formula for a compound with 40% sulfur and 60% oxygen?

Back

SO2

Front

What is the empirical formula for P2O4?

Back

PO2