To solve this, we need the solubility constant for Hg2Cl2, which is:
Ksp = 1.4 x 10^-18
The ionic formula would be:
Hg2Cl2(s) ---> Hg2 2+(aq) + 2Cl-(aq)
Therefore the total amounts of ions produced = x M Hg2 2+ and 2x M Cl-
The formula for Ksp in this case is:
Ksp = [Hg2 2+] [Cl-]^2
1.4 x 10^-18 = (x) * (2x)^2
1.4 x 10^-18 = 4x^3
x = 7.0 x 10^-7 M = [Hg2 2+]
2x = 14 x 10^-7 M = [Cl-]