posted by Anonymous on .
When 10.0 mL of 0.012 M pb(NO3)2 is mixed with 10.0 mL of 0.030 M KI, a yellow precipitate of PbI2(s) forms.
a)Calculate the molarity of [Pb^2+]
b)Calculate the initial molarity of [I^-]
c)On measuring the equilibrium concentrations of [I^-] it came out to be 8.0 x 10^-3 M. Calculate the molarity of [I^-] precipitated.
The problem looks simple enough; however, after reading and re-reading it I don't understand it at all. Do you know Ksp? Do you want the concn Pb^+2 before mixing, after mixing but before pptn of PbI2? For part b, molarity of I^- before mixing or after mixing and before or after pptn of PbI2.
For part c, if M = moles/L of soln and PbI2 is a ppt (and insoluble), how can it make sense to calculate a M?
this is what the question exactly says
Do you know Ksp?
no it is not given
The best I can do is leave this for another tutor. Perhaps another tutor can make sense of it. Personally, I think the problems needs to be clarified.