1. Stoich I

2. If I have 288 quarters, how many dimes can I make?
If I have 4 bags of chocolate chips, how many cookies can I make?
Both have simple mathematical solutions to solve these and so does stoichiometery!

3. Stoichiometry is a method to determine how much of a chemical is produced, or how much is needed, in a reaction.
All it is, is multiplication and division!

4. How many pesos in 100 rubles?
13 pesos in a dollar
36 rubles in a dollar
How many pesos in 100 rubles?
100 rubles
1 dollar
13 pesos
36 rubles
=36.1 pesos

5. Mole to Mole Conversion
If I have the formula 2H2 + O2 -> 2H2O, how many moles of hydrogen do I need to react with 1 mol of oxygen?
How many moles of hydrogen to I need to react with 5 moles of oxygen?
2 mol H2
10 mol H2

6. Dimensional Analysis Practice
Lead will react with hydrochloric acid to produce lead (II) chloride and hydrogen. How many moles of hydrochloric acid are needed to react with 0.36 moles of lead?
Pb(s) + 2HCl(aq) -->PbCl2(s) + H2(g)
0.36 mol Pb
2 mol HCl
1 mol Pb
=0.72 mol HCl

7. Dimensional Analysis Always start with what you know.
Set it up so the units cancel.
Nitrogen monoxide burns in oxygen to produce nitrogen dioxide.
How many moles of product are produced when 16 moles of oxygen are consumed?

8. Write a balanced chemical equation for the combustion of propane (C3H8).
If 6 mol of propane are reacted, how many moles of carbon dioxide will be formed?
C3H8 + 5O2 -> 3CO2 + 4H2O

9. If 17 moles of oxygen are used, how many moles of water vapor will be formed?
If 24 moles of water vapor are formed, how many moles of propane were reacted?
If 33 moles of carbon dioxide were formed, how many moles of water vapor are produced?
If 9 moles of oxygen are used, what is the total number of moles of products formed?

10. Stoich II
This is moles to grams or grams to moles. We need to be able to figure out how much substances weigh!
Remember formula weight? The total weight of all the atoms in a compounds.

11. Example
A caprese sandwich needs two pieces of bread (100 g), 5 slices of tomatoes (150 g), 4 pieces of mozarella (200 g) and 2 tbs of olive oil (20 g). If we have a package of mozzarella that weighs 440 g, how many sandwiches will it make?
440 g
1 mol tomato
1 sandwich
200 g
=2.2 sandwiches

12. 4NH3(g) + 6NO(g)→5N2(g) + 6H2O(g)
If we have 42.0 g ammonia, how many moles of nitrogen gas will be produced?
We need to find the formula weight of ammonia!
17.03 g/mol
42.0 g NH3
1 mol NH3
5 mol N2
17.03 g NH3
4 mol NH3
=3.08 mol N2

13. 4NH3(g) + 6NO(g)→5N2(g) + 6H2O(g)
How many grams of nitrogen monoxide is needed to react with 9.7 mol ammonia?
We need the formula weight of nitrogen monoxide!
9.7 mol NH3
6 mol NO
30.0 g NO
4 mol NH3
1 mol NO
=436.5 g NO

14. Heptane (C7H16) reacts with oxygen.
C7H O2 -> 7CO2 + 8H2O
If 17 g of heptane are burned, how many moles of oxygen are needed?
If 22 moles of oxygen are used, how many grams of each product are formed?
27.9 g of carbon dioxide is produced by how many moles of heptane?

15. Stoich III
Grams to grams! We need to know the molar mass of both substances we are talking about.
Example. Assume 6 large eggs, 1 cup of cheese (weighs 250 g) and 1 cup of veggies (weighs 400g) make 2 veggie omelets (each weighs 428 g). If I have 290 g cheese, how many grams of omelets am I making?
290 g cheese
1 c cheese
2 omelets
428 g
250 g cheese
1 omelet
= g omelet

16. Benzene (C6H6) is burned in air
Write a balanced chemical equation.
2C6H6 + 15O2 -> 12CO2 + 6H2O
If 1200 g of the carbon dioxide are formed, how many g of the water are produced?
If 475 g of the non-carbon product are formed, how many grams of each reactant were used?

17. The chemical reaction in this example is of environmental interest
The chemical reaction in this example is of environmental interest. Iron pyrite (FeS2) is often an impurity in coal, and so burning this fuel in a power plant produces sulfur dioxide, a major air pollutant. It also produces iron (III) oxide.
4 FeS2 (s) + 11 O2 (g) → 2 Fe2O3 (s) + 8 SO2 (g)

18. 4 FeS2 (s) + 11 O2 (g) → 2 Fe2O3 (s) + 8 SO2 (g)
How many grams of sulfur dioxide are produced when g of iron pyrite are burned?
How much oxygen is needed to react with 5.2 kg of iron pyrite?

19. How many grams of magnesium metal are required to react with 35 grams of nitrogen gas to produce magnesium nitride?
What mass of lead(II) bromide are formed when a solution containing 2.45 grams of potassium bromide are mixed with a solution containing 5.86 grams of lead(II) nitrate? (hint: 2 products are formed!)