Solubility-Product Constant

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Solubility-Product Constant
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Solubility-Product Constant

• is an equilibrium expression for a chemical
  equation that represents the dissolving of an
  ionic compound
• Ksp The product of the concentration of a
  salts ions in a saturated solution, each raised
  to the appropriate power.
• A large Ksp means that the compound is very
  soluble (forward reaction is favored)
• A small Ksp means the compound is not very
  soluble (reverse reaction is favored)

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Ksp Practice Problems

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Dissolving Problems

• Ksp is a measure of solubility it is not actual
  solubility (as in grams per liter). We can
  compute the how much will dissolve from the Ksp
  value.
• Steps to determine how much will dissolve
• Write the equation for the reaction
• Write the Ksp expression
• Get Ksp from the table
• Take the appropriate root
• Convert to grams/liter

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Practice Problems
How many grams of MgCO3 can be dissolved in 1.00
L of water if at 50C, the Ksp 2.5x10-5?

•  

• Take the appropriate root
• 2.5x10-5 Mg2 CO32-
• Mg2 CO32- 5.0x10-3M
• Convert to grams/liter
• (5.0x10-3 mol/L)(84.32 g/mol)
• 0.42 g/L

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Practice Problems
How many grams of FeS will dissolve per liter if
at 44, the Ksp 3.7x10-19?
 

• Take the appropriate root
• 3.7x10-19 Fe3 S2-
• Fe3 S2- 6.1x10-10M
• Convert to grams/liter
• (6.1x10-10 mol/L)(87.92 g/mol)
• 5.4x10-8 g/L

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Practice Problems

• How many grams of AgBr can be dissolved in 2.00 L
  of water if at 20C, the Ksp 4.8x10-13?
• How many grams of Ca(OH)2 will dissolve in one
  liter of water if at 15C, the Ksp 1.3x10-6?