A lab technician adds 0.110 mol of KOH to 1.00 L of 0.0010 M Ca(NO3)2. Ksp = 6.5

ID: 969088 • Letter: A

Question

A lab technician adds 0.110 mol of KOH to 1.00 L of 0.0010 M Ca(NO3)2. Ksp = 6.5 × 10-6 for Ca(OH)2. Which of the following statements is correct?

a)Calcium hydroxide precipitates until the solution is saturated.

b)The solution is unsaturated and no precipitate forms.

c)The concentration of calcium ions is reduced by the addition of the hydroxide ions

d)One must know Ksp for calcium nitrate to make meaningful predictions on this system.

e)The presence of KOH will raise the solubility of Ca(NO3)2. and please explain the answer

KOH K+ + OH-

1 1 1 mole ratio

.110 .110 .110 moles /L

Ca(NO)2 Ca+2 + 2 NO3 -

1 1 2 mole ratio

.0010 .0010 .0020 moles per Litre

Ionic product of Ca(OH)2 = conc of Ca+2 * conc of OH - ions = 0.0020*0.110 = 2.2*10^-4

Now 2.2*10^-4 (ionic product of Ca(OH)2 > 6.5*10^-6( solubility product oof Ca(OH)2

so Ca(OH)2 will ppt

answer : (a) Calcium hydroxide precipitates until the solution is saturated. is correct statement

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