In: Chemistry
Consider the equilibrium in the reaction below, the activities and the Debye-Hucke equation (if necessary), determine the solubility of HgBr2 as the concentration of Hg^2+ dissolved in the presence of 0.070 M NaBr. Kps= 1.3 x1-^-9 (HgBr2)
HgBr2(s) <----> HB^+2 + 2Br-
NaBr is strong electrolyte and it dissociate completely into Na+ and Br-
So,
initially, [Br-] = 0.070 M
HgBr2(s) <----> HB^+2 (aq) + 2Br- (aq)
0 0.070 (initial)
+s +2s (change)
s 0.070+2s (equilibrium)
Ksp = [HB^+2] [Br-]^2
1.3*10^-9 = s* (0.070+2s)
since ksp is small, s will be small and can be ignored as compared to 0.070.
Above expression thus becomes,
1.3*10^-9 = s* (0.070)
s = 1.9*10^-8 M
Answer: 1.9*10^-8 M