What are empirical and molecular formulas?

1 Answer
Aug 25, 2016

molecular formulas are the formula for the complete balanced compound. Empirical formulas are simplest ratio of the atoms and ions in the complete balanced formula .


For an example Glucose sugar has a molecular formula of # C_6 H_12 O_6 #

dividing everything by six gives a ratio of # C_1 H_2 O_1#

This is the empirical formula #C_1 H_2 O_1#

This is important because experimentally it is possible to find the percentage mass of each atom in the compound. The ratio of the percentage masses often gives the empirically formula, not the molecular formula.

For the above formula for glucose sugar, the percentages would be
Carbon 41.4% Hydrogen 3.45% Oxygen 55.2 %

This would give the empirical formula of #C_1 H_2 O_1#

As Carbon needs to form four bonds it is clear that the empirically formula can not be balance complete molecular formula.