Question

At a certain temperature, K = 9.1 10-4 for the following reaction.
FeSCN2+(aq)= Fe3+(aq) + SCN -(aq)

Calculate the concentrations of Fe3+, SCN -, and FeSCN2+ in a solution that is initially 4.0 M FeSCN2+.



OKAY SO i started by doing an ice table

with FeSCN2+(aq)= Fe3+(aq) + SCN -(aq)
I 4 M 0 0
C -x x x
E 4-x x x

and then solving for K
K=prod/react

and then quadtratic formula

how is this wrong?

Answer 1

What makes you think it's wrong? I can't tell much about your set up due to the fact that the boards don't allow spacing; however, I think you have gone about it right. If I solve the quadratic equation right, the (Fe^+3) = (SCN^-) = about 0.06 and (FeSCN^+2) = about 3.96

Answer 2

You can assume 5 % dissociation! You should get the right answer if you do that.