Question 1
A solution is prepared from 3.5 × 102mL of 3.2 M Pb(NO3)2 and 2.0×102 mL of 0.020 M NaCl. Given that Ksp for lead chloride is 1.6×10-5, what is the equilibrium concentration of the chloride ion?
Reference: Ref 16-1
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3.9 × 10–4◦
8.0 × 10–6◦
2.8 × 10–3◦
6.1 × 10–2◦
None of these are correct.Question 2
An industrial plant processes its waste water through a sedimentation tank that removes hazardous metals by precipitating them as insoluble carbonate salts. If sodium carbonate is gradually added to the tank, what would be the order of precipitation of the metals, Pb2+, Cu2+, Hg22+, and Zn2+if each is ≈ 1.0 × 10–4M? ( Kspof PbCO3= 7.4 × 10–14, Kspof CuCO3= 1.4 × 10–10, Kspof Hg2CO3= 8.9 × 10–17, and Kspof ZnCO3= 1.4 × 10–11)
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Pb2+, Hg22+, Zn2+, Cu2+◦
Hg22+, Pb2+, Zn2+, Cu2+◦
Cu2+, Zn2+, Pb2+, Hg22+◦
Cu2+, Zn2+, Hg22+, Pb2+◦
All metal ions will precipitate at the same time.
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