General Chemistry 4th Edition University Science Books presented by Saping Leami

Question

General Chemistry 4th Edition University Science Books presented by Saping Leaming Sodium sulfate is slowly added to a solution containing 0.0500 M Ca2 (aq) and 0.0390 M Ag (ag) What will be the concentration of Ca2 (aq) when Ag:SO4(s) begins to precipitate? Solubility-product constants, Kap.can be found here. Number Ca What percentage of the Ca? (aq) can be precipitated from the Ag (aq) by selective precipitation? Number O Previous & Give Up & View Solution Check Answer Next Ext Y Hint about us carees privacy policy es of use contacts 2 10 ?0 F2 F3 OD FA F5 F6 F7

Explanation / Answer

Ag2SO4 <--> 2 Ag+ + SO42-
Ksp = 1.2X10^-5 = [Ag+]^2[SO42-]
1.2X10^-5 = (0.0390)^2[SO42-]
[SO42-] = 7.9 X 10^-3 M

Now, to get to the [Ca2+] at this point, you must know the Ksp for CaSO4 4.9X10^-5 M. Then,
Ksp = [Ca2+][SO42-] = 4.9X10^-5
4.9X10^-5 = [Ca2+](7.9X10^-3)
[Ca2+] = 6.2X10^-3 M

So, [Ca2+] has gone from 0.0500M to 6.2X10^-3 M
The % precipitated = [(0.050 – 6.2X10^-3) / 0.050] X 100 = 87.6% precipitated

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