Steps for solving equilibrium problems:

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• Steps for solving equilibrium problems
• 1. Write out the equation.
• 2. Balance the equation if it is not.
• 3. Make a chart. (ICEBOX)
• I initial
• C change
• E - equilibrium

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• e.g. What is the equilibrium constant for the
  reaction of
• HI (g) H2 (g) I2 (g)
• when the initial concentration of HI is 2.00M and
  the I2 at equilibrium is 0.214M. Balance the
  reaction.

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2 HI H2 I2
initial 2.00
change
equil .214
0
0
-
2(.214)
.214

.214

.214
1.57
add products
subtract reactants
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Use equilibrium numbers
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• Ex for the reaction
• N2 (g) 3H2 (g) 2NH3 (g)
• The initial N2 0.32 M and H2 0.66 M. At
  a certain temperature and pressure the
  equilibrium H2 is found to be 0.30M. What is
  the value of keq ?

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N2 3 H2 2NH3
initial 0.32 0.66
change
equil 0.30
0
-
-

0.12
0.36
.24
.24
0.20
add products
subtract reactants
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• Ex At a particular temperature, keq for the
• H2 (g) I2 (g) 2HI (g)
• has a value of 55.6. If the initial H2
  0.200M and the initial I2 0.200M, what is
  the equilibrium HI?
• If Keq is given and no other information, you
  will have x as your change.

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H2 I2 2HI
initial 0.200 0.200
change
equil
0
-

-
x
2x
x
2x
0.20-x
0.20-x
add products
subtract reactants
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Question was HI at equilibrium 2x 2(0.1577)
0.315 M
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• Assigment p 587 24 27.
• p 588 42