Question

A solution is prepared by mixing equal volumes of 0.1 M MgC1₂ and 0.3 M Na₂C₂O₄ at 293 K. Will MgC₂O₄ precipitate out?  (K_sp of MgC₂O₄ at 293K is 8.56 × 10^-5)

Answer 1

Equal volumes of two solutions are mixed. The concentrations of both solutions are halved.

Thus, `["Mg"^2+] = 0.1/2 = 0.05 "M"`

`["C"_2"O"_4^(2-)] = 0.3/2 = 0.15 "M"`

Ionic product of `"MgC"_2"O"_4 = ["Mg"^(2+)]["C"_2"O"_4^(2-)]`

= 0.05 × 0.15

= 7.5 × 10^-3 

Ionic product of > K_sp, MgC₂O₄ will precipitate.