Concentration using activity coefficients

Question

Find the concentration of I− in 0.010 M AgNO3 saturated with AgI. Include activity coefficients in the solubility-product expression. The 𝐾sp of AgI is 8.3×10^−17

what is the concentration of I?

Answer 1

Saturated AgI has Ag⁺ I & I^- concentrations that equal each other so setting each one to x the formula would be

x • x = 8.3E-17, which x equals 9.1E-11 =[Ag⁺] =[I^-] in a saturated solution. When 0.010M AgNO₃ is added now the [Ag⁺] = 0.010 - 9.1E-11 which equals ˜0.010 so [I^-] = 8.3E-17/0.01= 8.3E-15. This phenomena is called the common ion effect.˜