Empirical and Molecular Formulas

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

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

How do you determine the empirical formula from percent composition?

Back

Convert the percentages to grams, then to moles, and find the simplest ratio of the moles of each element.

Front

What is the relationship between empirical and molecular formulas?

Back

The molecular formula is a whole-number multiple of the empirical formula.

Front

If the empirical formula is CH2O, how do you find the molecular formula given the molar mass?

Back

Divide the molecular molar mass by the molar mass of the empirical formula to find the multiplier.

Front

What is the empirical formula of a compound with 40% carbon, 6.67% hydrogen, and 53.33% oxygen?

Back

The empirical formula is CH2O.

Front

How many atoms of carbon are in one molecule of CO2?

Back

There is 1 atom of carbon in one molecule of CO2.

Front

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

Back

The empirical formula is Mg3N2.

Front

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

Back

The molecular formula is K8S4O16.

Front

Can a molecular formula be the same as an empirical formula?

Back

Yes, if the compound consists of only one type of molecule, the empirical and molecular formulas are the same.