Chapter 8 Solutions

1
Chapter 8Solutions

• Solubility
• Percent Concentration
• Colloids and Suspensions

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Solubility

• The maximum amount of solute that can dissolve
  in a specific amount of solvent usually 100 g.
• g of solute
• 100 g water

3
Saturated and Unsaturated

• A saturated solution contains the maximum amount
  of solute that can dissolve.
• Undissolved solute remains.
• An unsaturated solution does not contain all the
  solute that could dissolve

4
Learning Check S1

• At 40?C, the solubility of KBr is 80 g/100 g
  H2O. Indicate if the following solutions are
• (1) saturated or (2) unsaturated
• A. ___60 g KBr in 100 g of water at 40?C
• B. ___200 g KBr in 200 g of water at 40?C
• C. ___25 KBr in 50 g of water at 40?C

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Solution S1

• At 40?C, the solubility of KBr is 80 g/100 g
  H2O. Indicate if the following solutions are
• (1) saturated or (2) unsaturated
• A. 2 Less than 80 g/100 g H2O
• B. 1 Same as 100 g KBr in 100 g of water
• at 40?C, which is greater than its
  solubility
• C. 2 Same as 60 g KBr in 100 g of water,
• which is less than its solubility

6
Temperature and Solubility of Solids

• Temperature Solubility (g/100 g H2O)
• KCl(s) NaNO3(s)
• 0 27.6 74
• 20C 34.0 88
• 50C 42.6 114
• 100C 57.6 182
• The solubility of most solids (decreases or
  increases ) with an increase in the temperature.

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Temperature and Solubility of Solids

• Temperature Solubility (g/100 g H2O)
• KCl(s) NaNO3(s)
• 0 27.6 74
• 20C 34.0 88
• 50C 42.6 114
• 100C 57.6 182
• The solubility of most solids increases with an
  increase in the temperature.

8
Temperature and Solubility of Gases

• Temperature Solubility (g/100 g H2O)
• CO2(g) O2(g)
• 0C 0.34 0.0070
• 20C 0.17 0.0043
• 50C 0.076 0.0026
• The solubility of gases (decreases or increases)
  with an increase in temperature.

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Temperature and Solubility of Gases

• Temperature Solubility (g/100 g H2O)
• CO2(g) O2(g)
• 0C 0.34 0.0070
• 20C 0.17 0.0043
• 50C 0.076 0.0026
• The solubility of gases decreases with an
  increase in temperature.

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Learning Check S2

• A. Why would a bottle of carbonated drink
  possibly burst (explode) when it is left out in
  the hot sun ?
• B. Why would fish die in water that gets too
  warm?

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Solution S2

• A. Gas in the bottle builds up as the gas
  becomes less soluble in water at high
  temperatures, which may cause the bottle to
  explode.
• B. Because O2 gas is less soluble in warm water,
  the fish may not obtain the needed amount of O2
  for their survival.

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Soluble and Insoluble Salts

• A soluble salt is an ionic compound that
  dissolves in water.
• An insoluble salt is an ionic compound that does
  not dissolve in water

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Solubility Rules

• 1. A salt is soluble in water if it contains any
  one of the following ions
• NH4 Li Na K or NO3-
• Examples
• soluble salts
• LiCl Na2SO4 KBr Ca(NO3)2

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Cl- Salts

• 2. Salts with Cl- are soluble, but not if the
• positive ion is Ag, Pb2, or Hg22.
• Examples
• soluble not soluble(will not dissolve)
• MgCl2 AgCl
• PbCl2

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SO42- Salts

• 3. Salts with SO42- are soluble, but not if the
  positive ion is Ba2, Pb2, Hg2 or Ca2.
• Examples
• soluble not soluble
• MgSO4 BaSO4
• PbSO4

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Other Salts

• 4. Most salts containing CO32-, PO43-, S2- and
  OH- are not soluble.
• Examples
• soluble not soluble
• Na2CO3 CaCO3
• K2S CuS

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Learning Check S3

• Indicate if each salt is (1)soluble or (2)not
  soluble
• A. ______ Na2SO4
• B. ______ MgCO3
• C. ______ PbCl2
• D. ______ MgCl2

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Solution S3

• Indicate if each salt is (1) soluble or
• (2) not soluble
• A. _1_ Na2SO4
• B. _2_ MgCO3
• C. _2_ PbCl2
• D. _1_ MgCl2