Question

The pH at which Ca(OH)2 starts to precipitate if the solution contains 5.5 M Ca2+ ions (Ksp of Ca(OH)2 = 5.5 x 10-6)
0 11
O 12
09
O 3​

Answer 1

Answer:

Let S M be the solubility of Ca(OH)

2

in pure water.

S

Ca(OH)

2

⇌

S

Ca

2+

2S

OH

−

K

sp

=[Ca

2+

][OH

−

]

Substitute values in the above expression.

4.42×10

−5

=S(2S)

2

or S=0.0223M

500 ml of solution contains 0.01115 moles of calcium ions.

The molarity of NaOH solution is 0.4 M. When it is mixed with equal volume of calcium hydroxide solution, its molarity is reduced to half, i.e., 0.2M.

[OH

−

]=0.2M