Question

The molar solubility of C a ( O H ) 2 was experimentally determined to be 0. 020 M. Based on this value, what is the K s p of C a ( O H ) 2 ?

Answer 1

Ksp =
`3.2*10^(-5)`

Step-by-step explanation:

If 0.020 M of Ca(OH)2 dissociates, then we can follow the Ksp formula.

Ksp =
`[A]^(a) [B]^(b)` Eq.1

`Ca(OH)2 -- > Ca^(2+) (aq) + 2 OH^(-) (aq)` Eq.2

`0.02M Ca(OH)2 -- > 0.02 M Ca^(2+) + 2*0.02 M OH^(-)`

Here, Ca is our A and since it has a coefficient of 1, a = 1

OH is our B. The concentration is doubled because there are 2 moles of OH per mole of Ca(OH)2. Due to this it also has a coefficient of two (Eq.2), making b = 2.

Ksp =
`[0.02][0.02*2]^(2)`

Ksp = 0.000032

Ksp =
`3.2*10^(-5)`