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Equilibrium

Question
CBSEENCH11006605

At 298K, the, solubility of silver chloride in water is 0·00188 gL. What is its Ksp?

Solution
Molecular mass of AgCl
                             =  108  + 35.5  = 143.5 
Solubility of AgCl in water = 0.00188 gL-1                                
      equals space fraction numerator 0.00189 over denominator 143 end fraction space mol space straight L to the power of negative 1 end exponent
      equals space 1.31 space cross times space 10 to the power of negative 5 end exponent space mol space straight L to the power of negative 1 end exponent
We Know,   AgCl space space rightwards harpoon over leftwards harpoon space space space Ag to the power of plus space plus space Cl to the power of minus
i.e.  1 mole of AgCl in solution gives 1 mole of  Ag+ ion and 1 mole of Clions. Hence in the solution
               open square brackets Ag to the power of plus close square brackets space equals space 1.31 space cross times space 10 to the power of negative 5 end exponent space mol space straight L to the power of negative 1 end exponent
open square brackets Cl to the power of minus close square brackets space equals space 1.31 space cross times space 10 to the power of negative 5 end exponent space mol space straight L to the power of negative 1 end exponent
Applying the law of solubility product, 
         straight K subscript sp space equals space open square brackets Ag to the power of plus close square brackets space open square brackets Cl to the power of minus close square brackets
space space space space space space equals left parenthesis 1.31 space cross times space 10 to the power of negative 5 end exponent right parenthesis thin space left parenthesis 1.31 space cross times space 10 to the power of negative 5 end exponent right parenthesis
space space space space space space equals space 1.7 space cross times space 10 to the power of negative 10 end exponent