Ch. 15-16 Test
Answers to the extra worksheet below:
1) Qsp=1.58E-14; yes!
2) 2.0E-15M
3) 2.4E-4M
4a) 1.4E-7
4b) 9.8E-19M
4c) 1.0E-16M
5) Qsp=1.5E-11; no!
6) [Ag+]=2.6E-4M
7) 0.1200M (it stayed the same!!!-not much carbonate left to react!)
8)0.128g KCl
9)PbSO4 is first, [Pb2+]=7.6E-5M (use solver for the second question!)
10) MgF2 first, 0.16% remains (very small, makes sense!)
11) 1.5E-7M
One more AP problem to see if you get it!
1) At 25 °C the solubility product constant, Ksp, for strontium sulfate, SrSO4, is 7.6 x 10¯7. The solubility product constant for strontium fluoride, SrF2, is 7.9 x 10¯10
(a) What is the molar solubility of SrSO4 in pure water at 25 °C?
(b) what is the molar solubility of SrF2 in pure water at 25 °C?
(c) An aqueous solution of Sr(NO3)2 is added slowly to 1.0 liter of a well-stirred solution containing 0.020 mole F¯ and 0.10 mole SO42¯ at 25 °C. (You may assume that the added Sr(NO3)2 solution does not materially affect the total volume of the system.) Which salt precipitates first? What is the concentration of strontium ion, Sr2+, in the solution when the first precipitate begins to form?
(d) As more Sr(NO3)2 is added to the mixture in (c) a second precipitate begins to form. At that stage, what percent of the anion of the first precipitate remains in solution?
Answers:
a)8.7E-4M
b)5.8E-4M
c) SrF2; [Sr2+]=2.0E-6M
d) 50%