Question

Will a precipitate form when 250.0 mL of 0.330 M Na2CrO4 is added to 250.0 mL of 0.12 M AgNO3? KSP for silver chromate is 1.1 x 10-12.

Please show your work instead of just yes or no, thank you!

Answer 1

Lets find the concentration after mixing for AgNO3

Concentration after mixing = mol of component / (total volume)

M(AgNO3) after mixing = M(AgNO3*)V(AgNO3)/(total volume)

M(AgNO3) after mixing = 0.12 M*250.0 mL/(250.0+250.0)mL

M(AgNO3) after mixing = 6*10^-2 M

So,

[Ag+] = 6*10^-2 M

Lets find the concentration after mixing for Na2CrO4

Concentration after mixing = mol of component / (total volume)

M(Na2CrO4) after mixing = M(Na2CrO4*)V(Na2CrO4)/(total volume)

M(Na2CrO4) after mixing = 0.33 M*250.0 mL/(250.0+250.0)mL

M(Na2CrO4) after mixing = 0.165 M

So,

[CrO42-] = 0.165 M

The salt dissolves as:

Ag2CrO4 <----> 2 Ag+ + CrO42-

Qsp = [Ag+]^2[CrO42-]

Qsp = (6*10^-2)^2*(0.165)

Qsp = 5.94*10^-4

we have,

Ksp = 1.1*10^-12

Since Qsp is greater than ksp, precipitate will form