Stoichiometry IIStoichiometry II

REMEMBERREMEMBER

ALL stoichiometry problems start ALL stoichiometry problems start with awith a

balanced equationbalanced equation

How to do Mass-MassHow to do Mass-MassProblemsProblems

1.1. Balance the equationBalance the equation2.2. Convert the mass into moles (divide Convert the mass into moles (divide

by molar mass)by molar mass)3.3. Multiply the correct mole ratioMultiply the correct mole ratio4.4. Convert the moles into mass Convert the moles into mass

(multiply by molar mass)(multiply by molar mass)

ExampleExample How many grams of iron will react How many grams of iron will react

with 8.8 grams of oxygen?with 8.8 grams of oxygen?

Fe + OFe + O22 FeO FeO

Mole-Mass ProblemsMole-Mass Problems

You may be given the moles of one You may be given the moles of one substance and be asked to find the substance and be asked to find the mass in grams of another substance.mass in grams of another substance.

Mole-Mass ProblemsMole-Mass Problems

1. Balance the equation1. Balance the equation 2. Multiply the moles given by the 2. Multiply the moles given by the

correct mole ratiocorrect mole ratio 3.Convert the moles into mass 3.Convert the moles into mass

(multiply by molar mass)(multiply by molar mass)

Example Example

How many grams of FeO will be How many grams of FeO will be produced from 20.8 moles of produced from 20.8 moles of oxygen?oxygen?

Fe + OFe + O22 FeO FeO

Mass-MoleMass-Mole

If you are given a mass, in grams, of If you are given a mass, in grams, of one substance and asked to find the one substance and asked to find the number of moles of another number of moles of another substance.substance.

Mass-MoleMass-Mole

1. Balance the equation1. Balance the equation 2. Convert the mass given into moles 2. Convert the mass given into moles

(divide by molar mass)(divide by molar mass) 3. Multiply by the correct mole ratio3. Multiply by the correct mole ratio

ExampleExample

How many moles of FeO will be How many moles of FeO will be produced if 50 grams of Fe is reacted produced if 50 grams of Fe is reacted with excess oxygen?with excess oxygen?

Fe + OFe + O22 FeO FeO