Stoichiometry  “Branch of chemistry dealing with mass and mole relationships”
***Balance your equations to know how many moles will be involved with each part of the equation…
Balanced Equation: 2NaCl + MgO  Na2O + MgCl2 Complete the statement: ____ moles of NaCl will react with ____
mole of MgO to produce ___ mole of Na2O and ____ mole of MgCl2.
Mole Ratio: The ratio of moles in a compound. What is the mole ratio MgO =
MgCl2
2Al2O3  4Al + 3O2
Moles Al2O3: _____
Mole Ratios: mol Al2O3 =
mol Al
Moles Al: _____
mol O2
=
mole Al2O3
O2 =
H2O
H2O =
O2
4 Types of Stoichiometry Problems:
Moles O2: _____
mol Al =
mol O2
Your turn: First, balance the equation, then determine the mole ratios:
Mole Ratios: H2 =
H2O
NaCl =
MgCl2
a) Mole-Mole
mol Al =
mol Al2O3
____ O2 + ____H2  ____ H2O
H2 =
O2
b) Mole-Mass
c) Mass-Mole
d) Mass-Mass
MOLE-MOLE PROBLEMS: Problems where you start with moles of one substance and want to calculate the moles of
another substance.
Example 1 of Mole-Mole Problem:
Na + Cl2  NaCl For this equation, how many moles of NaCl can be produced from 18 moles of Na?
18 mol Cl2= __?__ mol NaCl
First, balance the equation so you know the ratios of all of the moles. 2 Na + Cl2  2NaCl
18 mol Cl2 2 mol NaCl = 36 mol NaCl
1 mol Cl2
Example 2 of Mole-Mole Problem:
NaOH + H2SO4  Na2SO4 + H20
From the equation, 5 moles NaOH = ______ moles Na2SO4
First, you must balance the equation so you know the mole ratios 2NaOH + H2SO4  Na2SO4 + 2H20
5 moles NaOH = ______ moles Na2SO4
5 mol NaOH
1 mol Na2SO4 = 2.5 mol Na2SO4
2 mol NaOH
______________________________________________________________________________________________
1.
H2 +
O2 
H20
6 mol H2 = ____ mol H20 **Don’t forget to balance equations!
2.
N2 +
H2 
NH3
8 mol NH3 = ____ mol N2
3.
Al +
O2 
Al2O3
63 mol O2 = ____ mol Al2O3
4.
Zn +
HCl 
ZnCl2 +
H2
45 mol HCl = ____ mol ZnCl2
MOLE-MASS PROBLEMS: Problems where you start with moles and are trying to end up with mass (in grams)
Example 1 of Mole-Mass Problem: N2 + H2  NH3
First step is always to balance your equation:
5 mol N2
2 mol NH3
1 mol N2
17.03052 g NH3
1 mol NH3
5 mol N2 = _____ grams NH3
N2 + 3H2  2NH3
= 170.3052 grams NH3
The formula
mass of NH3
Mole ratio of
NH3: N2
Example 2 of Mole-Mass Problem: KClO3  KCl + O2
18 mol KClO3 = _____ grams O2
Balance your equation: 2KClO3  2KCl + 3O2
18 mol KClO3
1.
P+
3 mol O2
2 mol KClO3
O2 
2.
Ag2O 
3.
K+
31.9988 g O2 = 863.9676 grams
1 mol O2
P2O5
4 mol P = ____ grams P2O5
Ag + O2
MgBr2  KBr +
4.
H2O +
O2 
5.
NaBr +
CaF2 
8 mol Ag2O = _____ grams Ag
Mg
H2O2
NaF +
21 mol MgBr2 = _____ grams KBr
5 mol O2 = ____ grams H2O2
CaBr2
9 mol CaF2 = ____ grams NaF
MASS-MOLE PROBLEMS: Problems where you start with mass (in grams) and are trying to end up with moles
Example 1 of Mass-Mole Problem: Ag2O  Ag + O2
First step is always to balance your equation:
30 g Ag2O
1 mol Ag2O
231.7354 g Ag2O
1 mol Ag__
2 mol Ag2O
30 grams Ag2O = _____ moles Ag
2Ag2O  4Ag + O2
= 0.0647 mol Ag
Mole ratio
of Ag:Ag2O
Formula mass
of Ag2O
Example 2 of Mass-Mole Problem: Fe + F2  FeF3
1239 grams F2 = _____ moles FeF3
Balance your equation: 2Fe + 3F2  2FeF3
1239 grams F2
1 mole F2
37.996806 grams F2
O2 
1.
Fe +
2.
HgO 
3.
Cu +
AgNO3 
4.
Ba +
H2SO4 
5.
O2 +
H2 
1 mol FeF3 = 10.869 mol FeF3
3 mol F2
Fe2O3
900 grams Fe = ____ moles Fe2O3
O2
47 grams HgO = _____ moles Hg
Hg +
H20
Cu(NO3)2 +
H2 +
BaSO4
Ag
35 grams Cu = _____ mol Cu(NO3)2
150 grams H2SO4 = ____ mol H2
36 grams O2 = ____ moles H2O
MASS-MASS PROBLEMS: Problems where you start with the mass of one substance and are trying to find the
related mass of another substance in the equation.
Example 1 of Mass-Mass Problem: KClO3  KCl+ O2
2KClO3  2KCl+ 3O2
First step is always to balance your equation:
80 grams KClO3
1 mol KClO3
122.5495 grams KClO3
80 grams KClO3 = _____ grams O2
3 mol O2
1 mol KClO3
Example 2 of Mass-Mass Problem: Na + Cl2  NaCl
31.9988 g O2 = 62.666 g O2
1 mol O2
35 grams Cl2 = _____ grams NaCl
Balance your equation: 2Na + Cl2  2NaCl
35 grams Cl2
1 mol Cl2
70.906 grams Cl2
2 mol NaCl
1 mol Cl2
58.44277 g NaCl = 57.696 g NaCl
1 mol NaCl
1.
Ag2S 
2.
NaClO3 
3.
H2 +
4.
NH3 
5.
K+
Cl2 
KCl
135 grams K = ____ grams KCl
6.
N2 +
F2 
NF3
7364 grams N2 = ____ grams NF3
Ag +
S8
NaCl +
O2 
N2 +
H2O
H2
78 grams Ag2S = _____ grams S8
O2
389 grams NaClO3 = _____ grams NaCl
965 grams H2 = _____ grams H2O
1375 grams NH3 = ____ grams H2