Sulfide \(\left(\mathrm{S}^{2-}\right)\) salts are notoriously insoluble in aqueous solution.
a. Calculate the molar solubility of nickel(II) sulfide in water. \(K_{\mathrm{sp}}(\mathrm{NiS})=3 \times 10^{-16}\)
b. Nickel(II) ions form a complex ion in the presence of ammonia with a formation constant \(\left(K_{f}\right)\) of \(2.0 \times 10^{8}\): \(\mathrm{Ni}^{2+}+6 \mathrm{NH}_{3} \rightleftharpoons\left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+}\). Calculate the molar solubility of NiS in \(3.0 \ \mathrm{M} \ \mathrm{NH}_{3}\).
c. Explain any differences between the answers to parts a and b.
Text Transcription:
(S^2-)
K_sp(NiS) = 3 x 10^-16
(K_f)
2.0 x 10^8
Ni^2+ + 6 NH_3 rightleftharpoons [Ni(NH_3)_6]^2+
3.0 M NH_3
Chapter 13: Chemical Kinetics 13.1 The Rate of Reaction Overview o Chemical kinetics: the area of chemistry concerned with the speed or rate, at which a chemical reaction occurs Kinetic = movement or chance o Kinetic energy: the energy available because of the motion of an object o Reaction rate: the chance in the concentration of a reactant or a product with time (M/s) Reactions can range from 1 millionth of a second to millions of years … it all depends o General equation: Reactants products Reactants consumed + products formed Monitoring: o Decrease in concentration of reactants o Increase in concentration of products A B Rate = ∆A / ∆t o Needs negative sign to make rate positive o A is decreasing & therefore a negative value Rate = ∆B / ∆t ∆A / B are changes in concentration (molarity) over time Reaction of Molecular Bromine and Formic Acid o Br 2 HCOOH (aq) 2 Br (aq) + 2H (aq) + CO (g) 2 Bromine reddishbrown in color As reaction takes place, concentration decreases & solution loses color
