Question

0.05 grams od cobalt ii oxalate will dissolve in one liter of solution at 25 degree celcius. Calculate the ksp for cobalt ii oxalate at 25 degree celcius

Answer 1

The equilibrium expression is:

CoC2O4(s)⇌Co2+(aq)+C2O2−4(aq)

For this reaction:

Ksp = [Co2+][C2O2−4]=1.96×10−8

Step-by-step explanation:

Batteries will not clot if cobalt ions are removed from its cells. Some blood collection tubes contain salts of the oxalate ion,

C2O2−4

, for this purpose. At sufficiently high concentrations, the calcium

and oxalate ions form solid, CoC2O4·H2O (which also contains water bound in the solid). The concentration of Co2+ in a sample of blood serum is 2.2 × 10–3M. What concentration of

C2O2−4

ion must be established before CoC2O4·H2O begins to precipitate.

CoC2O4 does not appear in this expression because it is a solid. Water does not appear because it is the solvent.

Solid CoC2O4 does not begin to form until Q equals Ksp. Because we know Ksp and [Co2+], we can solve for the concentration of

C2O2−4

that is necessary to produce the first trace of solid: