(NR) Jan 10th, 2011: Empirical Formula & Molecular Formula

- Empirical Formula are the simplest formula of a compound.

- Show only the simplest ratios, not the actual atoms.

• The empirical formula for Chlorine gas is Cl, not Cl2 ([*chlorine is diatomic] its reduced to its lowest factor)
• N2O4 becomes NO2 (reduced and divisible by 2)

- Molecular formulas give the actual number of atoms

- To determine the Empirical formula we need to know the ratio of each element.

When you're making your chart be sure to have the following for FULL marks!

1. ATOM
2. MASS
3. MOLAR MASS
4. MOLES
5. MOLE/SMALLEST MOLE
6. RATIO

*MUST BE MEMORIZED!

- The simplest ratio may be decimals. For certain decimals you need to multiply everything by a common number.

MOLECULAR FORMULAS

- The empirical formula to find the molecular formula you need the molar mass. 
*With this chart you should be given one information for each side!
** YOU MUST ALSO KNOW AND MEMORIZE THIS CHART FOR FULL MARKS!


_________________EMPIRICAL FORM.                   MOLECULAR FORM.______

FORMULA:

MOLAR MASS: