1. Happy Birthday RFK (1925) Mastering Chemistry
New assignment will be posted later today
Due Sunday by 11:59PM

2. Molecular Formulae: The Next Step
What is the empirical formula of:
C6H9N3
ratio = 3 to 1
C2H3N
What are the molar masses of the molecular and empirical formulae?
C6H9N3 = g/mol
ratio = 3 to 1
C2H3N = g/mol

3. Molecular Formulae: The Next Step
Molecular formula and empirical formula will always have the same ratio as the molecular mass and the empirical mass!
If a compound has a molar mass of g/mol and an empirical formula of CH, what is the molecular formula?
empirical mass = g/mol
mass ratio = 6 to 1
formula ratio = 6 to 1
6(CH)  C6H6
molecular formula = C6H6

4. Molecular Formulae: The Next Step
Caffeine is my life blood! Give the empirical and molecular formulae based on: 40.09g C, 4.172g H, 23.41g N, and 13.37g O. The molar mass of caffeine is g/mol
C4H5N2O

5. Molecular Formulae: The Next Step
Caffeine is my life blood! Give the empirical and molecular formulae based on: 40.09g C, 4.172g H, 23.41g N, and 13.37g O. The molar mass of caffeine is g/mol
C4H5N2O
C4H5N2O = g/mol
mass ratio = 2 to 1
formula ratio = 2 to 1
2(C4H5N2O)  C8H10N4O2
molecular formula = C8H10N4O2

6. Molecular Formulae: The Next Step
Give the empirical and molecular formulae for a compound based on: 6.85g C, 0.432g H, 3.41g O, and 11.4g Br. The molar mass of the compound is g/mol
~ 4 mol C
~ 3 mol H
~ 1.5 mol O
1 mol Br
C8H6O3Br2

7. Molecular Formulae: The Next Step
Give the empirical and molecular formulae for a compound based on: 6.85g C, 0.432g H, 3.41g O, and 11.4g Br. The molar mass of the compound is g/mol
C8H6O3Br2 = g/mol
C8H6O3Br2
mass ratio = 3 to 1
formula ratio = 3 to 1
3(C8H6O3Br2)  C24H18O9Br6
molecular formula = C24H18O9Br6

8. You analyze a g sample of 18-crown-6 (a specific crown either) and find that there are g of carbon and g of oxygen in the sample with the rest being hydrogen.
a) What are the percents of carbon and oxygen in the sample of 18-crown-6?
What is the percent of hydrogen in 18-crown-6?
What is the empirical formula of 18-crown-6?
18-crown-6 has a molar mass of g/mol. What is the molecular formula?