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 molecular formula from the empirical formula?

Back

To find the molecular formula, multiply the subscripts in the empirical formula by a whole number that makes the molecular mass equal to the given mass.

Front

What is the empirical formula for a compound with 40.05% sulfur and 59.95% oxygen?

Back

SO3

Front

Which of the following pairs has the same empirical formula: NaCrO4 and Na2Cr2O7, or C2H4O2 and C6H12O6?

Back

C2H4O2 and C6H12O6 have the same empirical formula.

Front

What is the relationship between molecular and empirical formulas?

Back

The molecular formula is a multiple of the empirical formula.

Front

If a compound has an empirical formula of CH2O, what could be its molecular formula?

Back

C2H4O2 is a possible molecular formula.

Front

What is the significance of the molecular mass in determining the molecular formula?

Back

The molecular mass helps to identify how many times the empirical formula must be multiplied to obtain the molecular formula.

Front

How do you convert percentages to an empirical formula?

Back

Convert the percentages to grams, then to moles, and simplify the mole ratio to find the empirical formula.

Front

What is the empirical formula for C6H12O6?

Back

The empirical formula is CH2O.