Empirical and Molecular Formula

Front

What is an empirical formula?

Back

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

Front

How do you determine the empirical formula from percent composition?

Back

Convert the percent composition to grams, then to moles, and find the simplest whole-number ratio.

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 of a compound is CH2 and its molar mass is 42 g/mol, what is the molecular formula?

Back

C3H6.

Front

What is the formula to calculate the molar mass of a compound?

Back

Add the atomic masses of all the atoms in the molecular formula.

Front

What is the significance of the molar mass in determining molecular formulas?

Back

The molar mass helps to find how many times the empirical formula fits into the molecular formula.

Front

How do you convert an empirical formula to a molecular formula?

Back

Divide the molar mass of the compound by the molar mass of the empirical formula, then multiply the subscripts in the empirical formula by this ratio.

Front

What is the empirical formula of a compound with 40% carbon and 60% oxygen by mass?

Back

CO.

Front

What is the empirical formula of a compound with 50% sulfur and 50% oxygen by mass?

Back

SO.