Given that for Ca(OH)2, Ksp=4.8×10−6, will precipitation occur if a 125⋅mL volume of calcium chloride at 2.9×10−2⋅mol⋅L−1 concentration is mixed with a 175⋅mL volume of sodium hydroxide at 2.9×10−2⋅mol⋅L−1 concentration?

1 Answer
anor277
Mar 20, 2017

We interrogate the equilibrium:

Ca2++2HO−⇌Ca(OH)2(s)⏐⏐↓

FOR which Ksp=4.8×10−6

Explanation:

Now we are given that Ksp=4.8×10−6=[Ca2+][HO−]2.

And thus we must work out the concentrations with respect to Ca2+ and HO−, and determine the initial ion product........Q

Ca2+=

Moles of calcium ionvolume of solution=0.125⋅L×2.9×10−2⋅mol⋅L−10.125⋅L+0.175⋅L

=0.0121⋅mol⋅L−1

HO−=

Moles of hydroxide ionvolume of solution=0.175⋅L×2.9×10−2⋅mol⋅L−10.125⋅L+0.175⋅L

=0.0169⋅mol⋅L−1

And the ion product Q=[Ca2+][HO−]2=3.46×10−6⋅mol⋅L−1

Since Ksp=4.8×10−6 > Qion product, precipitation SHOULD NOT occur..........

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