# Hints for solving Stoichiometry Problems

This document was developed by S.E. Van Bramer for Chemistry 145 at Widener University.

## First the hamburger analogy

### My recipe for a bacon double cheeseburger is:

• 1 hamburger bun
• 2 hamburger patties
• 2 slices of cheese
• 4 strips of bacon

### Based on this recipe:

1. If I have five bacon double cheeseburgers:
1. How many hamburger buns do I have?
2. How many hamburger patties do I have?
3. How many slices of cheese do I have?
4. How many strips of bacon do I have?

2. How many bacon double cheeseburgers can you make if you start with:
1. 1 bun, 2 patties, 2 slices of cheese, 4 strips of bacon
2. 2 bun, 4 patties, 4 slices of cheese, 8 strips of bacon
3. 1 dozen bun, 2 dozen patties, 2 dozen slices of cheese, 4 dozen strips of bacon
4. 1 mole bun, 2 mole patties, 2 mole slices of cheese, 4 mole strips of bacon
5. 10 bun, 20 patties, 2 slices of cheese, 40 strips of bacon

3. If you had fixings for 100 bacon double cheeseburgers, but when you were cooking you ruined 10 of them. What percentage of the bacon double cheeseburgers do you actually make?

## Now, the chemistry problem.

NOTE: The math and the concepts are identical to the above example. The only difference is the recipe.

1. Given 1 mole of NaCl
1. Calculate the moles of sodium
2. Calculate the moles of chloride
3. Calculate the mass of sodium
4. Calculate the mass of chloride
5. Calculate the mass of sodium chloride

2. Given 1 mole of methane (CH4)
1. Calculate the moles of carbon
2. Calculate the moles of hydrogen
3. Calculate the mass of carbon
4. Calculate the mass of hydrogen
5. Calculate the mass of methane

3. Given 1 mole of ethanol (C2H6O)
1. Calculate the moles of carbon
2. Calculate the moles of hydrogen
3. Calculate the moles of oxygen
4. Calculate the mass of carbon
5. Calculate the mass of hydrogen
6. Calculate the mass of oxygen
7. Calculate the mass of ethanol

4. Given 2 grams of ethanol (C2H6O)
1. Calculate the moles of carbon
2. Calculate the moles of hydrogen
3. Calculate the moles of oxygen
4. Calculate the mass of carbon
5. Calculate the mass of hydrogen
6. Calculate the mass of oxygen
7. Calculate the mass of ethanol

Scott Van Bramer
Department of Chemistry
Widener University
Chester, PA 19013