What are empirical and molecular formulas?
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
dividing everything by six gives a ratio of
This is the empirical formula
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
As Carbon needs to form four bonds it is clear that the empirically formula can not be balance complete molecular formula.