Transcript Chapter 8 Solutions

Chapter 7 Solutions and Colloids
7.2
Solubility
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
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Solubility
Solubility is
• the maximum amount of solute that dissolves in a
specific amount of solvent.
• expressed as grams of solute in 100 grams of solvent
water.
g of solute
100 g water
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Unsaturated Solutions
Unsaturated solutions
• contain less than the
maximum amount of
solute.
• can dissolve more solute.
Dissolved
solute
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
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Saturated Solutions
Saturated solutions
• contain the maximum
amount of solute that
can dissolve.
• have undissolved solute
at the bottom of the
container.
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
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Supersaturated Solutions
Supersaturated solutions
• An unstable solution that
contains an amount of
solute greater than the
solute solubility.
• Also has undissolved
solute at the bottom of
the container.
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
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Learning Check
At 40C, the solubility of KBr is 80 g/100 g H2O.
Identify the following solutions as either
1) saturated or (2) unsaturated. Explain.
A. 60 g KBr added to 100 g of water at 40C.
B. 200 g KBr added to 200 g of water at 40C.
C. 25 g KBr added to 50 g of water at 40C.
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Solution
A. 2
Amount of 60 g KBr/100 g water is less than the
solubility of 80 g KBr/100 g water.
B. 1
In 100 g of water, 100 g KBr exceeds the
solubility of 80 g KBr water at 40C.
C. 2
This is the same as 50 g KBr in 100 g of water,
which is less than the solubility of 80 g KBr/100
g water at 40C.
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Effect of Temperature on Solubility
Solubility
• Depends on
temperature.
• Of most solids
increases as
temperature
increases.
• Of gases decreases
as temperature
increases.
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Learning Check
A. Why could a bottle of carbonated drink possibly
burst (explode) when it is left out in the hot sun ?
B. Why do fish die in water that is too warm?
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Solution
A. The pressure in a bottle increases as the gas
leaves solution as it becomes less soluble at high
temperatures. As pressure increases, the bottle
could burst.
B. Because O2 gas is less soluble in warm water, fish
cannot obtain the amount of O2 required for their
survival.
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Solubility and Pressure
Henry’s Law states
• the solubility of a gas
in a liquid is directly
related to the
pressure of that gas
above the liquid.
• at higher pressures,
more gas molecules
dissolve in the liquid.
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