Stoichiometry II
REMEMBER

ALL stoichiometry problems start with a
balanced equation
How to do Mass-Mass
Problems
1.
2.
3.
4.
Balance the equation
Convert the mass into moles (divide by
molar mass)
Multiply the correct mole ratio
Convert the moles into mass (multiply by
molar mass)
Example

How many grams of iron will react with
8.8 grams of oxygen?
Fe
+ O2
FeO
Mole-Mass Problems

You may be given the moles of one
substance and be asked to find the mass
in grams of another substance.
Mole-Mass Problems
1. Balance the equation
2. Multiply the moles given by the correct
mole ratio
3.Convert the moles into mass (multiply by
molar mass)
Example

How many grams of FeO will be produced
from 20.8 moles of oxygen?
Fe + O2
FeO
Mass-Mole

If you are given a mass, in grams, of one
substance and asked to find the number
of moles of another substance.
Mass-Mole
1. Balance the equation
2. Convert the mass given into moles
(divide by molar mass)
3. Multiply by the correct mole ratio
Example
How many moles of FeO will be produced
if 50 grams of Fe is reacted with excess
oxygen?
Fe + O2
FeO