Empirical and Molecular Formulas

Front

What is an empirical formula?

Back

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

Front

Can empirical and molecular formulas be the same?

Back

Yes, for some compounds, the empirical and molecular formulas can be identical.

Front

What is the relationship between empirical and molecular formulas?

Back

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

Front

What lab equipment is used to determine the molar mass of a compound?

Back

A mass spectrometer is used to determine the molar mass of a compound.

Front

If the empirical formula of a compound is CH2, what could be its molecular formula?

Back

Possible molecular formulas include C2H4, C3H6, C4H8, etc.

Front

True or False: A whole-number ratio exists between the molecular formula and the empirical formula of a compound.

Back

True.

Front

True or False: Knowing the empirical formula gives you the exact number of atoms in a molecule.

Back

False. The empirical formula only provides the simplest ratio.

Front

What does it mean if a compound has a molecular formula of C6H12?

Back

It means the compound contains 6 carbon atoms and 12 hydrogen atoms.

Front

How do you calculate the empirical formula from percent composition?

Back

Convert the percentages to grams, then to moles, and simplify the mole ratio to the smallest whole numbers.