Question

Which of the following solution has greater density?

1. 100ml of saturated aqueous solution of Lif. (Ksp(Lif)=1.84*10^-3).

2. 100ml of saturated aqueous solution of Hg2F2. (Ksp(Hg2F2)=3*10^-6).

(We can assume that adding the dissolved doesn't change the volume of the solution).

Explanation would be appreciated.

Answer 1

Use the Ksp values for LiF and Hg2F2 to calculate the solubility of each salt in 100 mL H2O. Then, since density = mass/volume, and the volume is the same, the one with the larger mass will have the largaer density.

Answer 2

So please tell what am I doing wrong here.

As far as I understand the concentration of Lif is the square root of it's ksp=sqrt(1.84*10^-3)=0.043.

Now, 0.043=n/100ml, and by multiplying both sides of the equation by 25.941 (the Mw of Lif) I get that the solubility of Lif in 100ml of water is 1.12g/100ml (which according to wikipedia is wrond...).