Answer
(a) No, there will be no precipitation.
(b) Yes, there will be precipitation.
Work Step by Step
(a)
1. Write the $K_{sp}$ expression:
$ NiCO_3(s) \lt -- \gt 1Ni^{2+}(aq) + 1CO_3^{2-}(aq)$
$ K_{sp} = [Ni^{2+}]^ 1[CO_3^{2-}]^ 1$
2. Find the $Q_{sp}$ value
$ Q_{sp} = (2.4 \times 10^{-3})^ 1 \times (1.0 \times 10^{-6})^ 1$
$ Q_{sp} = 2.4 \times 10^{-9}$
$K_{sp} (NiCO_3) = 1.4 \times 10^{-7}$
Since $Q_{sp} \lt K_{sp}$, there will be no precipitation
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(b)
1. Write the $K_{sp}$ expression:
$ NiCO_3(s) \lt -- \gt 1Ni^{2+}(aq) + 1CO_3^{2-}(aq)$
$ K_{sp} = [Ni^{2+}]^ 1[CO_3^{2-}]^ 1$
2. Find the $Q_{sp}$ value
$ Q_{sp} = (2.4 \times 10^{-3})^ 1 \times (1.0 \times 10^{-4})^ 1$
$ Q_{sp} = 2.4 \times 10^{-7}$
$K_{sp} (NiCO_3) = 1.4 \times 10^{-7}$
Since $Q_{sp} \gt K_{sp}$, there will be precipitation
