Question

In an experiment, it is planned to add 300 m L of 2.0x105 M AgNO3 to 200 mL of 2.5 × 109 M Nal. Will a precipitate form? What is the precipitate? Ksp(Agl) 8.3 x10 a. yes, the ppt is AgNO:(s) b. yes, the ppt is NaNO3(s) c. yes, the ppt is Nal(s) "d. yes, the ppt is Agl(s) 17 e. no

Answer 1

AgNO3(aq) + NaI(aq) -----------> AgI(s) + NaNO3(aq)

AgI (s) <----------------> Ag+ + I-

Ksp = [Ag+][I-]

Q also has the same expression as Ksp usig the concentrations at any give time and called ionic product

If ionic product Q > Ksp precipitation occurs.

let us calculate [Ag+] and[I-] in the given solution.

[Ag+] in the solution after mixing = 300x 2.0x10^-5 / (300+200)

=1.2x10^-5

[I-] in solution aftermixing = 200x2.5 x10^-9/ 500

= 1.0x10^-9

Thus ionic product Q = 1.2x10^-5 x1.0x10^-9

= 1.2x10^-14

This is greater than the Ksp 8.3x10^-17

Thus a precipitate of AgI is formed.