CHM 151(cont.) 8. From each of the following ion concentrations in a solution, p
ID: 1009326 • Letter: C
Question
CHM 151(cont.)
8. From each of the following ion concentrations in a solution, predict whether a precipitate will form in the solution.
a.) [Mg2+] = 0.0065 M, [CO32-] = 0.0058 M
Ksp = 3.5 x 10-8
b.) [Ag+] = 0.046 M, [SO42-] = 0.0055 M
Ksp = 1.4 x 10-5
9. How many moles of calcium chloride can be added to 0.80L of 0.012 M K2CO3 before a precipitate is expected? Assume that the volume of the solution is not changed significantly by the addition of calcium chloride.
10. Calculate the solubility (in grams per liter) of Zinc hydroxide, Zn(OH)2, in pure water.
Explanation / Answer
if Qsp(ionicproduct) > Ksp(solubility product) precipitation occurs.
so that,
8.
a. Qsp = 0.0065*0.0058 = 3.77*10^-5
qsp > ksp precipitation occurs.
b. qsp = 0.046^2*0.0055 = 1.164*10^-5
qsp < ksp precipitation donot occurs
9. ksp of Caco3 = 3.36*10^-9
ksp = s^2 = 3.36*10^-9
solubility = 5.8*10^-5 M
solubility PER 0.8 L = 5.8*10^-5*0.8 = 4.64*10^-5 mol
so that
No of mol of CaCl2 can be added = 4.64*10^-5 mol
10. ksp of Zn(OH)2 = 3*10^-17
3*10^-17 = 4S^3
solubility = 1.96*10^-6 M
in g/L = 1.96*10^-6*99.424 = 1.95*10^-4 g/L