Help for the chem homework this week

Hi folks,

I'm including the steps to these empirical formula problems.  They are the same thing that you should have in your notes but  just in case…. :)

Also, I'm going to indicate which problems each set of steps goes with for the homework worksheet.  Hopefully this will help make these a bit smoother to tackle. 

A. Finding empirical masses if you know masses of elements

1. Divide masses of the elements given in the problem by their molar mass
2. Divide all answers by smallest answer found in #1.
3. Find smallest whole # for all

B. Empirical formulas with percentages  Problem 1,2

1. Assume you have 100 g of the compound so that the percentages can be the same as masses.
2. Divide each percentage by it's molar mass
3. Divide all answers by smallest answer found in #2.
4. Find smallest whole #'s for all atoms in the molecule.

C. Empirical formulas with mass of molecule  Problems 3, 4, 5 (remember percentages can be used like  masses)

1. Divide mass of each element given by the total mass of molecule to find percentage of element in the molecule.
2. Divide those masses by the molar mass of each element.
3. Divide all by smallest answer found in #2
4. Find smallest whole #'s for all

D. Going from Empirical to Molecular from molar mass of molecule  Problems 6, 7, 8

1. Find the molar mass of the empirical formula
2. Divide molar mass given by empirical formula's molar mass.
3. Multiply each atom in the empirical formula)by answer to find Molecular formula

E. Going from empirical formula to molecular formula from masses of elements in compound  Problems 9, 10

1. Find empirical formula of compound (See either A or B)
2. Find Molar Mass of the empirical formula.
3. Divide molar mass given in problem by empirical formula molar mass
4. Multiply the atoms in the empirical formula by answer in step 3 to find molecular formula.