Empirical and Molecular Formula

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 mass percentages?

Back

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

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 is the molecular formula related to the empirical formula?

Back

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

Front

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

Back

Mg3N2.

Front

Given 42.07g Na, 18.89g P, and 39.04g O, what is the empirical formula?

Back

Na3PO4.

Front

What is the empirical formula for 40.05g S and 59.95g O?

Back

SO3.

Front

If the empirical formula is CF2 and the molecular formula mass is 192 g/mol, what is the molecular formula?

Back

C4F8.

Front

Which pair has the same empirical formula: NaCrO4 and Na2Cr2O7, or C2H4O2 and C6H12O6?

Back

C2H4O2 and C6H12O6.

Front

What is the first step in determining the empirical formula from a compound's composition?

Back

Convert the mass of each element to moles.