Mole – Mass
Stoichiometry
In a mole-mass problem, you are given
the mass or moles of one substance and
are asked to find the mass or moles of
another substance.
Solving Mole- Mass Problems
Convert the given mass to moles using
molar mass of given substance.
Given mass of substance “A”
molar mass of substance “A” = Mol “A”
STEP 1 – Mass  Mole
Determine the number of moles for the
unknown by using molar ratio of the
coefficients in the balanced equation.
Mol “A” x molar ratio “B” = Mol “B”
“A”
STEP 2 – Mole to Mole
Determine the number of moles for the
unknown by using molar ratio of the
coefficients in the balanced equation.
Mol “A” x molar ratio “B” = Mol “B”
“A”
STEP 1 – Mole to Mole
Convert the number of moles of the
unknown to mass by using molar mass of
unknown substance.
Mol “B” x molar mass of substance “B” = Mass “B”
STEP 2 – Mole  Mass
1.
In a reaction between the elements aluminum and
chlorine, aluminum chloride is produced.
2Al + 3Cl2  2AlCl3
a. How many grams of AlCl3 will be produced if
2.50 moles of Al react?
Practice Problems (mol – g)
b. How many moles of Cl2 must react to
produce 12.3 g of AlCl3?
2Al + 3Cl2  2AlCl3
(g – mol)
c. How many grams of aluminum will react
with 3.4 moles of chlorine?
2Al + 3Cl2  2AlCl3
(mol – g)
d. If 17 grams of aluminum react, how
many moles of aluminum chloride will
be produced?
2Al + 3Cl2  2AlCl3
(g – mol)