Transcript Observing Changes to Equilibrium - Forestville Middle

Observing Changes to
Equilibrium
Forestville Central School
Regents Chemistry
Introduction
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
In this experiment you will be introduced to chemical
equilibrium.
You will then be presented with a number of systems at
equilibrium and will be asked to "stress" these systems by
changing the concentration of one of the reactants or products
or by changing the temperature of the system.
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Experiments
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Complete each one of the experiments below and answer the
questions on your worksheet. Click on the pictures to guide you.
Cobalt System
Chromate
System
Ammonium
System
Iron Thiocyanate
System
Copper Sulfate
System
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Cobalt System
3)
1)
4)
2)
CoCl4
2-
5)
Hint: Think about
The Cl- ion
Hint: read the
note below
NOTES: - Silver ions react with chloride ions to form the insoluble compound silver chloride.
Cobalt System
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1) Answer:
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Equilibrium shifts to the left
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Cobalt System
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2) Answer:
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Equilibrium shifts to the right
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Cobalt System
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3) Answer:
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Equilibrium shifts to the Right
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Cobalt System
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4) Answer:
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Equilibrium shifts to the left
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Cobalt System
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5) Answer:
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Equilibrium shifts to the right due to the
precipitation out of the Cl- ions in AgCl.
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Ammonium System
pink
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Colorless
1)
2)
NOTES: - The purplish color is due to phenolphthalein.
The darker the purple color, the larger the hydroxide ion concentration in solution.
Ammonium System
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1) Answer:
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Equilibrium shifts to the right (see notes regarding
color)
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Ammonium System
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2) Answer:
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Increase in temperature shifts the equilibrium to the
RIGHT
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Iron Thiocyanate
1)
2)
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3)
4)
NOTES: - the HPO4-2 ion forms a complex with the Fe+3 ion.
Hint:
See notes
Iron Thiocyanate
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1) Answer:
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Equilibrium shifts to the Right
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Iron Thiocyanate
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2) Answer:
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Equilibrium shifts to the right
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Iron Thiocyanate
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3) Answer
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Equilibrium shifts to the left
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Iron Thiocyanate
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4) Answer
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Due to the removal of Fe+3, equilibrium shifts to the
left
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Chromate System
1)
2)
Na2CrO4
Na2Cr2O7
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Chromate System
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1) Answer:
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Equilibrium shifts to the right
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Chromate System
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2) Answer:
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Equilibrium shifts to the left
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Copper Sulfate System
Copper Sulfate System
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Answer:
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Equilibrium shifts to the right as water is heated off
Question:
What if you add water
Back to the dish?
Copper Sulfate System
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Answer:
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Equilibrium shifts back to the left as water is added
back to the unhydrated crystal