Question

Ecell - Ford
3 The solubility product (Ksp) of Mg(OH)2 at 25 °C is 5.6 x 10-11. Its solubility in water is
S x 10-2 g/L, where the value of S is 273 (up to two decimal places).
(Given: Molecular weight of Mg(OH)2 = 58.3 g mol-)
1,39​

Answer 1

Explanation:

Mg(OH)

2

⇌Mg

2+

+2OH

−

S 2S

K

sp

=[Mg

2+

][OH

−

]

2

=(S)(2S)

2

=4S

3

=5×10

−19

So S=5×10

−7

means [OH

−

]=2S=10

−6

So pOH=−log([OH

−

])=6

As we know pH+pOH=14

So pH=8