Mole
Stoichiometry
The study of quantitative
relationships between the
amounts of reactants used and
products formed by a chemical
reactions; it is based on the law
of conservation of mass.
Mole
The SI base unit used to
measure the amount of a
substance.
Avogadro’s Number
The number of representative
particles in a mole, and can be
rounded to three significant
digits:
6.02 X 1023 molecules/mol
Molarity
moles/L =M
Molecule
Forms when two or
more atoms covalently
bond.
To find the number of
molecules it takes to equal a
certain number of moles. Take
the number of moles given and
multiply by Avogadro’s number.
How many molecules of Sucrose is
in 3.50 moles of Sucrose.
3.50 mol Sucrose X
23
6.02x10 molecules/mol
=2.11x1024molecules of
Sucrose
How many molecules of Sodium
Hydroxide is in 4.80 moles of
Sodium Hydroxide?
4.80 mol Sodium Hydroxide X
23
6.02x10 molecules/mol
=2.89x1024 molecules of Sodium
Hydroxide
To find the number of moles it
takes to equal a certain number
of molecules. Take the number
of molecules given and divide
by Avogadro’s number.
How many moles of Sucrose is
24
in 3.54x10 molecules of
Sucrose.
24
3.54x10
molecules of
Sucrose ÷
23
6.02x10 molecules/mol
=5.88 moles of Sucrose
How many moles of Sodium
24
Hydroxide is in 5.63x10
molecules of Sodium Hydroxide.
5.63x1024 molecules NaOH ÷
23
6.02x10 molecules/mol
=9.35 moles of NaOH
Molar Mass
The mass in grams of
one mole of any pure
substance.
g/mol
To find the number of grams of
substance. Take the number of
moles given and multiply by
the substance’s molar mass.
Find the mass of 3.2 moles of
Butane needed to complete the
reaction.
3.2 mol of Butane X
58.14 g/mol
=186.05 g of Butane
Find the mass of 4.5 moles of
Pentanol needed to complete
the reaction.
4.5 mol Pentanol X
86.15 g/mol
=387.68 g of Pentanol
To find the number of moles of
substance. Take the number of
grams given and divide by the
substance’s molar mass.
Find the moles of 23 g of water
needed to complete the
reaction.
23 g water ÷
18.02 g/mol
=1.28 mol of water
Find the moles of 112 g of
Hydrochloric Acid needed to
complete the reaction.
112 g of Hydrochloric Acid ÷
36.46 g/mol
=3.07 mol of Hydrochloric Acid
To find the number of moles of
an element in a compound,
multiply the moles of the
compound with the ratio of
number of elements to 1 mol of
compound.
How many moles of Fluorine is
found in 5.50 moles of Freon
(CCl2F2).
5.50 mol CCl2F2 X
2 mol F atoms/1 mol CCl2F2 =
11.0 mol F atoms
How many moles of Oxygen is
found in 4.75 moles of Glucose
(C6H12O6).
4.75 mol C6H12O6 X
6 mol O atoms/1 mol C6H12O6
= 28.5 mol O atoms
To find the moles of a
compound, take the mass of
the compound and divide by
the molar mass of the
compound.
How many moles are there of
47g of water?
47g of water ÷
18.02 g/mol of water
= 2.61 mol of water
How many moles are there of
21g of Benzene?
21g of Benzene ÷
78.12 g/mol of Benzene
= 0.27 mol of Benzene
Mole Ratio
In a balanced equation,
the ration between the
numbers of moles of any
two substances.
To find mole ratio, put moles of
one substance over the moles of
another substance in chemical
equation.
2KClO3 → 2KCl + 3O2
2mol KClO3/2mol KCl
2 mol KClO3/3mol O2