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Stoichiometry
Introduction to Stoichiometry
Stoichiometry

Objectives

Define stoichiometry

Describe the importance of the mole ratio in stoichiometric
calculations

Write a mole ratio relating two substances in a chemical
equation
Stoichiometry

Stoichiometry Definitions

Composition stoichiometry deals with the mass
relationships of elements in compounds

Reaction stoichiometry involves the mass relationships
between reactants and products in a chemical reaction
Stoichiometry

Reaction Stoichiometry Problems

Problem Type 1: Given and unknown quantities are
amounts in moles
Amount of given
substance (mol)
Amount of unknown
substance (mol)
Stoichiometry

Reaction Stoichiometry Problems

Problem Type 2: Given is an amount in moles and
unknown is a mass
Amount of given
substance (mol)
Amount of unknown
substance (mol)
Mass of unknown
substance (g)
Stoichiometry

Reaction Stoichiometry Problems

Problem Type 3: Given is a mass and unknown is an
amount in moles
Mass of given
substance (g)
Amount of given
substance (mol)
Amount of unknown
substance (mol)
Stoichiometry

Reaction Stoichiometry Problems

Problem Type 4: Given is a mass and unknown is a mass
Mass of a given substance (g)
Amount of given
substance (mol)
Amount of unknown
substance (mol)
Mass of unknown
substance (g)
Stoichiometry

Mole Ratio

A mole ratio is a conversion factor that relates the amounts
in moles of any two substances involved in a chemical
reaction
2Al2O3(l) → 4Al(s) + 3O2(g)
2 mol Al2O3
4 mol Al
,
2 mol Al2O3
3 mol O2
,
4 mol Al
3 mol O2
Stoichiometry

Converting Between Amounts in Moles
Stoichiometry

Stoichiometry Calculations
Stoichiometry

Stoichiometry Calculations

Sample Problem

For each equation, balance and write all possible mole ratios
HgO (s)
NH3 (g) + NO (g)
Hg (l) + O2 (g)
N2 (l) + H2O (l)
Stoichiometry

Stoichiometry Calculations

Sample Problem

How many moles of sodium will react with water to produce 4.0
mol of hydrogen in the following reaction?
Na(s) + H2O(l)  NaOH(aq) + H2(g)
Stoichiometry

Stoichiometry Calculations

Sample Problem

How many moles of lithium chloride will be formed by the
reaction of chlorine with 0.046 mol of lithium bromide in the
following reaction?
LiBr(aq) + Cl2(g)  LiCl(aq) + Br2(l)
Stoichiometry

Stoichiometry Calculations

Sample Problem

Aluminum will react with sulfuric acid in the following reaction.
Al(s) + H2SO4(l)  Al2(SO4)3(aq) + H2(g)

How many moles of H2SO4 will react with 18 mol Al?

How many moles of each product will be produced from 18 mol
Al?
Stoichiometry

Stoichiometry Calculations

Sample Problem

Propane burns in excess oxygen according to the following
reaction.
C3H8 + O2  CO2 + H2O

How many moles each of CO2 and H2O are formed from 3.85
mol of propane?

If 0.647 mol of oxygen is used in the burning of propane, how
many moles each of CO2 and H2O are produced? How many
moles of C3H8 are consumed?