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I dont understand how solubility product (Ksp) work?

  1. Nov 3, 2012 #1
    Suppose the Ksp value of AgCl is 2 x 10^-10.

    Lets say we have a saturated solution of AgCl, i.e concentration of Ag+ ions = concentration of Cl+ions = (2 x 10^-10)^0.5=1.41 x 10^-5

    Ok so what i know is that if we add more Ag+ ions in the solution, precipitation of AgCl would occur since ionic product is greater than Ksp.

    So lets say we add Ag+ ions such that the concentration of Ag+ ions is now 2x10^-4 moldm^-3.

    Here is the part i dont understand.

    The remaining chloride concentration would be 2x10^-10 divided by 2x10^-4 mol = 1x10^-6 moldm^-3. My question is where did the chloride ions go? i know it has precipitated but it doesnt make sense since the concentration of Ag+ ions did not decrease?
  2. jcsd
  3. Nov 4, 2012 #2


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    Why would the concentration of Ag+ need to decrease? You have shown the Cl- concentration decreases from 1.41X10-5 to 1X10-6 so to maintain the Ksp product, Ag+1 must be higher.
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