Question

Solid AgCl (Ksp = 1.8 X 10-10) is placed in a beaker of water. After a period of time, the Ag+ concentration is measured and found to be 2.5 X 10-7 M.
a) What is the concentration of Cl-?
b) Has the system reached equilibrium?
c) Will more AgCl dissolve?

Answer 1

Explanation:

a)

$k _{sp} = [Ag {}^{ + } ][Cl {}^{ - } ] \\ but \: [Ag {}^{ + } ] = [Cl {}^{ - } ] \\ k _{sp} = [Ag {}^{ + } ] {}^{2} \\ [Ag {}^{ + } ] = \sqrt{k _{sp}} \\ = \sqrt{1.8 \times {10}^{ - 10} } \\ = 1.34 \times {10}^{ - 5} mol {dm}^{ - 3}$

b)

It has not reached equilibrium because the silver concentration is not yet equal to the value of Ksp.

c)

Yes it will dissolve in order to establish the equilibrium.