1. and Empirical Formula

2.  Determine the mass percentage of each element in the compound.

3.  2 Fe  2 x 55.8 = 111.6 g  3 O  3 x 16.0 = 48.0 g  Formula mass = 159.6 g  % Fe =  % O = 70.0 % Fe 30.0% O

4.  Gives the lowest whole # ratio of elements in a compound.  The empirical formula for C 6 H 12 O 6 is  The empirical formula for C 2 H 6 is  * most basic ratio of elements in the compound CH 2 O CH 3

5.  X (empirical formula) = molecular formula  So.... X =  And...

6.  What is the molecular formula of the molecule that has an empirical formula of CH 2 O and a molar mass of 120.12 g/mol? ◦ We need to find the molar mass of the empirical formula first.

7.  Easy level ◦ C 4 H 8 O 4  What is the empirical formula?  Medium Difficulty ◦ The previous problem  Hardest Difficulty ◦ Next problem

8.  Find the empirical formula of a compound that contains 53.7% iron and 46.3% sulfur.  Steps: ◦ % composition  mass of 100g sample  moles  mole ratio 0.962 mol Fe 1.44 mol S

9.  Take smaller # and divide everything by it Fe 2 S 3