Stoichiometry
• Stoichiometry is a section of chemistry that involves
using relationships between reactants and products
in a chemical reaction to determine desired
quantitative data
• In a balanced reaction, both sides of the equation
have the same number of elements. The
stoichiometric coefficient is the number written in
front of atoms, ion and molecules to balance the
number of each element on both sides of the
equation
• 6CO2(g) + 6H2O(l)  1C6H12O6(s) + 6O2(g)
• The most common stoichiometric problem will
present you with a certain amount of a
reactant and then ask how much of a product
can be formed. Here is a generic chemical
equation:
3A+4B2D+1F
Steps for solving Stoichiometry
Problems
1. Balance the chemical equation
2. Convert the given mass to moles by using
molar mass or the substance
3. Construct a molar proportion between the
substances you are looking for
4. Using the molar mass of the unkown
substance, convert the moles just calculated
to mass.
Stoichiometry Road Map
aA + bB
cC + dD
Mass A
Mass B
Mol Ratio
Mol A
Atoms A
Molecules
Mol B
Atoms B
Molecules
3A+4B2D+1F
How many moles of F are produced from 1.00 mol of A?
1 mol A
1 mol F
3 mol A
How many moles of D are
produced from 5.00 mol of B?
5 mol B
2 mol D
4 mol B
= 2.50 mol D
= 0.333 mol F
Working a Stoichiometry Problem
6.50 grams of aluminum reacts with an excess of oxygen.
How many grams of aluminum oxide are formed?
1. Identify reactants and products and write the
balanced equation.
4 Al
+ 3 O2
2 Al2O3
a. Every reaction needs a yield sign!
b. What are the reactants?
c. What are the products?
d. What are the balanced coefficients?
4 Al
+ 3 O2
1. What is your starting point?
2. What is your ending point?
6.50 g Al
2 Al2O3
6.50 g of Aluminum
g of aluminum oxide
1 mol Al
2 mol Al2O3
101.96 g Al2O3
26.98 g Al
4 mol Al
1 mol Al2O3
6.50 x 2 x 101.96 ÷ 26.98 ÷ 4
= 12.3 g Al2O3
= ? g Al2O3
How many moles of lithium carbonate are produced
when 5.3 mol CO2 are reacted?
CO2(g) + 2LiOH(s)  Li2CO3(s) + H2O(l)
1. What is your starting point?
2. What is your ending point?
5.3 mol CO2
1 mol Li2CO3
1 mol CO2
= 5.3 mol Li2CO3
5.3 mol of CO2
mol of Li2CO3
3A+4B2D+1F
How many grams of F are produced from 1.00 mol of A? If MM
of F is 10.0g/mol.
1 mol A
1 mol F
3 mol A
10 g F
1 mol F
How many grams of D are
produced from 5.00 mol of B?
MM of D is 20.0g/mol
5 mol B
2 mol D
20 g D
4 mol B
1 mol D
= 50.0g D
= 3.33g F
What is the mass of glucose (C6H12O6) produced
from 3.00 mol of water (H2O)?
6CO2(g) + 6H2O(l)  C6H12O6(s) + 6O2(g)
1. What is your starting point?
2. What is your ending point?
3 mol H2O
1 mol
C6H12O6
6 mol H2O
=90.1 g C6H12O6
180.81g
C6H12O6
1 mol
C6H12O6
3.00 mol of H2O
g of C6H12O6
6CO2(g) + 6H2O(l)  C6H12O6(s) + 6O2(g)
What is the mass of oxygen (O2) produced from 2.50
mol of water (H2O)?
1. What is your starting point?
2. What is your ending point?
2.5 mol H2O
6 mol O2
32.0 g O2
6 mol H2O
1 mol O2
=80.0 g O2
2.50 mol of H2O
g of O2
4NH3(g) + 5O2(g)  4NO(g) + 6H2O(g)
How many moles of NO are formed from 824 g of NH3?
1. What is your starting point?
2. What is your ending point?
824 g NH3
1 mol NH3
4 mol NO
17.03g
4 mol NH3
= 48.4 mol NO
824 g of NH3
mol of NO
3A+4B2D+1F
How many grams of F are produced from 5.00g of A? If MM of
F is 10.0g/mol and MM of A is 25.0g/mol
5gA
1 mole A
1 mole F
10 g F
25 g A
3 mole A
1 mole F
How many grams of D are
produced from 5.00g of B?
MM of D is 20.0g/mol and
MM of B is 10.0g/mol
5gB
1 mole B
10 g B
=5.00g D
2 mole D
4 mole B
20 g D
1 mole D
= 0.677g F
Sn(s) + 2HF(g)  SnF2(s) + H2(g)
How many grams of SnF2 are produced from
the reaction of 30.00 g HF?
1. What is your starting point?
2. What is your ending point?
30.00g HF
1 mol HF
1 mol SnF2
20.01g HF
2 mol HF
= 117.5g SnF2
30.00 g of HF
g SnF2
156.71 g SnF2
1 mol SnF2
Real World Application
STOICHIOMETRY
• Think of a balanced chemical equation as a recipe; the
number of moles of each particle input (reactants)
indicates the amount of ingredients needed to prepare
the food, and the number of moles of each particle
output (products) indicates how much of each type of
final food one will end up with. The type of input that
will be used up first determines the maximum amount
of possible output.
Click Below for the Video Lectures
Stoichiometry