Question

Calculate the solubility of silver chloride in a 0.1 mol/L solution of sodium chloride at 25°C.?
At SATP, Ksp AgCl(s) = 1.8 x 10^-10

What did I do wrong?

AgCl <----> Ag+ + Cl-

[Ag+] = x
[Cl-] = x + 0.1

Ksp = [Ag+] [Cl-]

1.8 x 10^-10 = (x) ( x + 0.1)

x = molar solubility = 1.8 x 10^-9 M

Answer 1

I don't see an error. SATP refers to 25^o and that's what you have for Ksp. The solubility is certainly smaller than x + 0.1 so x + 0.1 certainly is almost 0.1. The only thing I can think of is that perhaps the problem wanted grams/L instead of molarity. And finally, I don't know the level of the class but sometimes one must make a correction for ionic strength and that can make a SMALL difference.