Question

Multiple Choice:

12. mulu5 pts.) An alloy contains 23.18 M of Praseodymium-143. The radioactive beta decay| of Praseodymium-143 to form Neodymium-143 occurs as a first-order reaction. The half-life of this reaction is 13.58 days. After a period of 75.38 days, the alloy still contains the following concentration of Pr-143: (a) 0.185 M (bilm2.16 M (c) 0.495 M (d) 0.346 M 14.15 pts.) A lump of silver carbonate, Ag2CO3, was placed in 450.0 mL of pure water. The Ksp for the dissolution of Ag2CO3 is 8.46 x 10-12 M3 and is described by: Ag2CO3 (s) + 2 Ag+ (aq) + CO32- (aq) After a length of time the equilibrium concentration of Ag+ ion in this solution would be: (a) 1.30 x 10-3 M (biltelZ x 10-3 M (c) 1.30 x 10-4 M (d) 2.57 x 10-4 M 15. (5 pts.) A chemist was working with a sample of 0.128 M HClO2. The value of Ka for this acid is 1.10 x 10-2 M. The dissociation of this acid is described by: HClO2 (aq) ++ H+ (aq) + ClO2 (ag) The % dissociation of the acid in this solution is: (a) 25.4% (b) 19.6% (c) 13.4% (dh.22.7%