Molecular and Empirical Formulas

Front

What is an empirical formula?

Back

An empirical formula represents the simplest whole-number ratio of the elements in a compound.

Front

How do you calculate the empirical formula from percentage composition?

Back

1. Convert percentages to grams. 2. Convert grams to moles. 3. Divide by the smallest number of moles to find the ratio.

Front

What is the empirical formula for a compound with 36.84% nitrogen and 63.16% oxygen?

Back

N₂O₃

Front

What is the empirical formula for a compound with 72.2% magnesium and 27.8% nitrogen?

Back

Mg₃N₂

Front

What is the empirical formula for P₂O₆?

Back

PO₃

Front

What is the empirical formula for a compound with 69.6% iron and 30.4% oxygen?

Back

Fe₂O₃

Front

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

Back

Multiply the subscripts in the empirical formula by a whole number to match the molecular mass.

Front

What is the molecular formula for a compound with the empirical formula K₂SO₄ and a molecular mass of 696g?

Back

K₈S₄O₁₆

Front

What is the difference between empirical and molecular formulas?

Back

The empirical formula shows the simplest ratio of elements, while the molecular formula shows the actual number of atoms in a molecule.

Front

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

Back

CH