1. Bellwork What is the mass of one mole of hydrogen peroxide, H2O2?
What is the mass of ten moles of hydrogen peroxide?

2. CHAPTER 7 THE MOLE

3. CALCULATING EMPIRICAL FORMULAS Empirical formula - lowest whole number ratio of the elements in a compound - may or may not be the same as the molecular formula.

4. Steps to calculate empirical formula: 1. Find moles of each element. 2
Steps to calculate empirical formula: 1. Find moles of each element. 2. Set up mole ratio.
3. Simplify mole ratio (divide by smallest). If your answers are not in whole numbers, you must multiply by 2,3,4,or 5 to get whole numbers. 4. Use mole ratio as subscripts in the formula. If given % composition, assume 100 g of compound.

5. Empirical Formula Poem
Percent to mass,
mass to moles,
divide by smallest and round ‘till whole!

6. A compound is 79.8% C and 20.2% H. Find its empirical formula.

7. A compound is 79.8% C and 20.2% H. Find its empirical formula.
/6.65 = 1
79.8gC 1mol C = mol C
12.0 g C
20.2 g H 1 mol H = 20.0 mol H
1.01 g H
CH3
/6.65 = 3

8. Find the empirical formula for a compound made up of 26. 7% P, 12
Find the empirical formula for a compound made up of 26.7% P, 12.1% N and 61.2% Cl.

9. Find the empirical formula for a compound made up of 26. 7% P, 12
Find the empirical formula for a compound made up of 26.7% P, 12.1% N and 61.2% Cl.
26.7 g P 1 mol P = mol P g P
12.1 g N 1 mol N = mol N g N
61.2 g Cl 1 mol Cl = mol Cl
35.5 g Cl
/0.861=1
/0.861=1
/0.861=2
Empirical Formula = PNCl2