nigamananda mishra
Last Activity: 7 Years ago
Solubility of Mg(OH)2 in pure water = 9.57 x 10-3 g/L
= 9.57 x 10-3 /molar mass mole/L
= 9.57 x 10-3 /58 mole/L = 1.65 x 10-4 mol/L
Ks for Mg(OH)2 = s x (2s)2 = 4s3
= 4 x (1.65 x 10-4 mol/L)3
= 17.96 x 10-12
Suppose, the solubility of Mg(OH)2 in the presence of Mg(NO3)2 = s'
So, Mg2+ = s'+c = s' + 0.02
[OH'] = 2s'
Therefore, Ks = (s' + 0.02) (2s')2
17.96 x 10-12 = 4 (s' + 0.02) (s')2
or, 17.96 x 10-12/4 = s'3 + 0.02 (s' )2 , on neglecting s'3
4.4921 x 10-12 = 0.02 (s' )2
(s' )2 = 14.98 x 10-6 mol/l
Solubility in g/l
= 14.98 x 10-6 x58 = 8.69 x 10-4 g/l
