Learning Goals
0 List the sequence of steps used in
solving stoichiometric problems.
0 Solve stoichiometric problems.
Using Stoichiometry
0 Steps to solve mole-to-mole, mole-
to-mass, and mass-to-mass
stoichiometric problems:
1. Write a balanced chemical equation
for the reaction.
2.Determine where to start your
calculations by noting the unit of the
given substance.
Using Stoichiometry
0 If mass (in grams) of the given
substance is the starting unit, you
must convert to moles.
0 If amount (in moles) of the given
substance is the starting unit,
convert moles of the given substance
to moles of the unknown.
Using Stoichiometry
3.The end point of the calculation
depends on the desired unit of the
unknown substance.
0 If the answer must be in moles, stop you
are finished.
0 If the answer must be in grams, convert
moles of unknown to grams of
unknown using the molar mass as the
conversion factor.
Example – Mole to Mole
0 Sodium chloride forms by the reaction
between sodium and chlorine. How many
moles of NaCl result from the complete
reaction of 3.4 mol of Cl2?
1. Write a balanced chemical equation:
Example – Mole to Mole
2. Decide which mole ratio to use:
Example – Mole to Mole
3. Use the mole ratio to convert the starting
number of moles to final number of
moles.
Example – Mole to Mass
0 Magnesium hydroxide neutralizes stomach acid,
HCl, to produce water and magnesium chloride.
What mass of HCl can be neutralized by 0.550
moles of Mg(OH)2?
1. Write a balanced chemical equation:
Example – Mole to Mass
2. Decide which mole ratio to use:
Example – Mole to Mass
3. Use the mole ratio to convert the starting
number of moles to final number of
moles, then use molar mass.
Example – Mass to Mass
0 If 2.72 g of KClO3(s) decompose into KCl(s) and
O2(g), then how many grams of oxygen are
produced?
1. Write a balanced chemical equation:
Example – Mass to Mass
2. Decide which mole ratio to use:
Example – Mass to Mass
3. Find the number of moles of the starting
substance using molar mass. Use the mole
ratio to convert the starting moles to final
number of moles, and then use the
second molar mass.