5.1 Decide Ksp-expr.:

a) PbF2

b) Ag2CrO4

Solutions:

a) Insert eq. of dissociation: PbF2 > Pb+2 + 2F- and calculate the Ksp-expr.

b) Insert eq. of dissociation: Ag2CrO4 > 2Ag+ + CrO4-2 and calculate the Ksp-expr.

5.2 Determine Ksp Ca(OH)2 if 0.0105 mol dissolves in 1 kg of water.

Solution:

Step 1) Insert equation of dissociation: Ca(OH)2 > Ca+2 + 2OH-

Step 2) Insert 0.0105 in the [Ca+2] field (Mass solvent = 1 kg)

Step 3) Calculate

5.3 How many grams of CdF2 dissolves in 1 kg of water when [F-] = 0.234 M ?

Solution:

Step 1) Insert equation of dissociation: CdF2 > Cd+2 + 2F-

Step 2) Insert 0.234 in the [F- ] field (Mass solvent = 1 kg)

Step 3) Calculate (CdF2)

5.4 How many grams of PbCl2 dissolved in 1 kg of water (Ksp=1.78E-5) when [Pb+2] = 0.01 M.

Solution:

Step 1) Insert equation of dissociation: PbCl2 > Pb+2 + 2Cl-

Step 2) Insert 1.78E-5 in Ksp-field (Mass solvent = 1 kg)

Step 3) Insert 0.01 in [Pb+2] common ion field

Step 4) Calculate

5.5 The solubility of Ag2CrO4 in pure water is 6.54E-5M. Show that the solubility of Ag2CrO4 in a 0.05M AgNO3 sol. is 4.48E-10M.

Solution:

Step 1) Insert equation of dissociation: Ag2CrO4 > 2Ag+ + CrO4-2

Step 2) Insert 6.54E-5 in mol-field (Mass solvent = 1 kg)

Step 3) Calculate solubility product.

Step 4) Insert 0.05 in [Ag+] common ion field

Step 5) Calculate

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