To a concentrated buffer of pH 9.0 was added an equal volume of an aqueous solution that was 0.20 M in each of the ions Ca²⁺,Cd²⁺,and Cu²⁺.The expected precipitate would consist of:
Salt: calcium hydroxide cadmium hydroxide copper(II) hydroxide
K_sp: 4.0 × 10^-6 2.0 × 10^-14 1.8 × 10^-19

Question

Quizplus · Accepted Answer

At pH 9, the concentration of OH⁻ ions is high enough to exceed the Ksp of both Cd(OH)₂ and Cu(OH)₂, causing them to precipitate. However, the Ksp of Ca(OH)₂ is much higher, so it remains soluble.

To a Concentrated Buffer of PH 9