STOICHIOMETRY
Cooking with Chemistry
If we want to know
how to make a
product, how do we
know the “recipe”
for making that
product?
Two Types of Stoichiometry
• Composition Stoichiometry – the conversions
between mass, moles, particles, and liters of a
substance.
• Reaction Stoichiometry – the conversions
between reactants and products in a chemical
reaction.
Concept Base
You must know how to
• Balance equations
• Calculate molar mass for any
substance
• Convert moles into grams
using molar mass
• Convert moles into particles
using 6.02 x 1023
• Interpret the meaning of a
balanced equation
Interpreting Equations
NO!
2C(s) + O2
 2CO(g)
22atoms
mole
g C CC++11molecule
gmole
O2 O
O22

 222gmole
molecules
CO CO
NO!!!
CO
Coefficients
Coefficients represent
• mole ratios
• particle ratios
• (and even the ratio of Liters for some gases as
we will see later)
BUT NEVER
• mass ratios.
2C(s) + O2(g)  2CO(g)
• Q1: How many moles of CO are produced
from the reaction of 2 moles of C with an excess
of O2?
A1: 2 moles CO
• Q2: How many moles of CO are produced
from the reaction of 1 mole of C with an excess
of O2?
A2: 1 mole CO
2C(s) + O2(g)  2CO(g)
• Q3: How many moles of CO are produced
from the reaction of 3.56 mol of C with an
excess of O2?
A3: 3.56 mol CO
• Q4: How many moles of CO are produced
from the reaction of 2.50 mol of O2 with an
excess of C?
2 mol CO
A4: 2.50 mol O 2 x
= 5.00 mol CO
1 mol O 2
2C(s) + O2(g)  2CO(g)
• Q5: How many grams of C are used in the
reaction to produce 3.00 moles of CO?
A5:
12.01 g C
2 mol C
3.00 mol COx
x
=
1 mol C
2 mol CO
= 36.0 g C
2C(s) + O2(g)  2CO(g)
• Q6: How many grams of C are used in the
reaction to produce 9.8 grams of CO?
A6:
1 mol CO
12.01 g C
2 mol C
x
9.8 g CO x
x
28.01 g CO 2 mol CO
1 mol C
= 4.2 g C
2C(s) + O2(g)  2CO(g)
• Q7:How many grams of O2 are used in the
reaction to produce 1.24 x 1024 molecules of
CO?
1 mol CO
x
23
molecules CO 
6.02 x 10 molecules CO
molecules CO mol CO
molecules CO mol CO mol O2
molecules CO mol CO mol O2 g O2
= 16.5 g O2
2C(s) + O2(g)  2CO(g)
• Q8: How many molecules of O2 are used in the
reaction to produce 3.4 moles of CO?
A8: 1.0 x 1024 molecules O2
• Q9: How many atoms of C are used in the
reaction to combine with 3.6 g of O2?
A9: 3.8 x 1022 atoms C
•
•
•
•
Molar Volume
Volume is the amount of space a material occupies
Volume is traditionally measured in liters.
1 Liter is half the size of a 2 Liter soda bottle.
If you had 6.02x1023 particles of O2, in a balloon,
what would the volume of the balloon be?
• All gases have the same volume per mole:
22.4 L/mol
• So if you have 6.02x1023 gas particles, you have 1
mole, and your balloon would be 22.4 Liters or about
12 soda bottles.
C6H12O6 + 6O2 → 6CO2+ 6H2O
( + Energy in the form of ATP)
• The basic process of cellular respiration by
which your body converts food energy into
stored energy is given above.
• What volume in liters of CO2 would be
produced if 450 grams of glucose was reacted
with excess O2?
• How many grams of glucose would be needed
to react completely with 122 liters of O2?
You Try It.
Do the Stoichiometry Worksheet #1.