SOLUTION
STOICHIOMETRY
DEFINITION OF TERMS
STOICHIOMETRY
- relationship between the relative
quantities of substances taking part in a
reaction or formation of a compound.
DEFINITION OF TERMS
Mole to mole ratio
- quantitative relationship between
the amounts of reactants and/or
products in a given chemical equation.
DEFINITION OF TERMS
Molar mass
- mass of one mole of substance,
usually measure in g/mol.
COMPUTATION
Balance the equation.
Convert starting unit of a given
substance to moles.
Using the mole ratio, calculate the
moles of substance yielded by the
reaction.
Convert moles of wanted
substance to required unit.
1. How many grams of calcium phosphate can be
produced from the reaction of 2.50 L of 0.250 M
calcium chloride with and excess of phosphoric acid?
CaCl2 + H3PO4
3CaCl2 + 2H3PO4
Ca3(PO4)2 + HCl
Ca3(PO4)2 + 6HCl
Given:
2.50 L CaCl2 ; 0.250 M CaCl2
3CaCl2 + 2H3PO4
Required: g of Ca3(PO4)2
Solution:
Ca3(PO4)2 + 6HCl
Convert starting unit to moles
2.50 L CaCl2 x
0.250 mol CaCl2
1 L solution
0.625 mol CaCl2 x
= 0.625 mol CaCl2
1 mol 𝐶𝑎3 (P𝑂4 )2
3 mol CaCl2
= 0.2083 mol Ca3(PO4)2
Mole ratio (Balanced chemical equation)
0.2083 mol Ca3(PO4)2 x
310.0 g 𝐶𝑎3 (P𝑂4 )2
1 mol
Convert moles to required unit
= 64.57 g Ca3(PO4)2
2. How many liters of 1.50 M Nitric acid is required to
react with 100 g of cuprous oxide?
HNO3 + Cu2O
14HNO3 + 3Cu2O
Cu(PO3)2 + NO + H2O
6Cu(PO3)2 + 2NO + 7H2O
Given:
1.50 M HNO3 ; 100 g Cu2O
14HNO3 + 3Cu2O
Required: L of HNO3
Solution:
6Cu(PO3)2 + 2NO + 7H2O
Convert starting unit to moles
100 g Cu2O x
0.6988 mol Cu2O x
1 mol Cu2 O
143.1 g
= 0.6988 mol Cu2O
14 mol HNO3
3 mol Cu2 O
= 3.2611 mol HNO3
Mole ratio (Balanced chemical equation)
3.2611 mol HNO3 x
1 L HNO3
1.50 mol HNO3
Convert moles to required unit
= 2.17 L HNO3
1. A technician needs to determine the concentration
of a sulfuric acid solution. In an experiment, a 10 mL
sample of sulfuric acid reacts completely with 15.9 mL
of 0.150 mol/L potassium hydroxide solution.
Calculate the molar concentration of the sulfuric acid.
H2SO4 + KOH
H2O + K2SO4
H2SO4 + 2KOH
2H2O + K2SO4
Given:
10 mL H2SO4
15.9 mL KOH ; 0.150mol/L KOH
H2SO4 + 2KOH
Required: M of H2SO4
Solution:
2H2O + K2SO4
Convert starting unit to moles
0.0159 L KOH x
2.385x10-3
0.150 mol CaCl2
=
1 L solution
mol KOH x
1 mol H2 SO4
2 mol KOH
2.385x10-3 mol KOH
= 1.1925x10-3 mol H2SO4
Mole ratio (Balanced chemical equation)
1.1925x10−3 mol H2SO4
0.01 L solution
Convert moles to required unit
=
0.12 M H2SO4
4. What volume of a 0.470 M HCl reacted with enough Zn
metal to produce 1.50 g ZnCl2 based on the following
reaction?
Zn + HCl
ZnCl2 + H2
5. Consider the following reaction:
Ca(OH)2 + HCl
CaCl2 + H2O
5a. How many liters 0.100 M HCl is required to completely
react with 5 grams of calcium hydroxide?
6. How many grams of Ca(OH)2 are needed to neutralize
25 mL of 0.100 M HNO3? The reaction proceeds as
follows:
HNO3 + Ca(OH)2
H2O + Ca(NO3)2