Chemistry
posted by UN .
The standard solution of FeSCN2+ (prepared by combining 9.00 mL of 0.200 M Fe(NO3)3 w/1.00 mL of 0.0020 M KSCN) has an absorbance of 0.510. If a trial's absorbance is measured to be 0.250 and its initial concentration of SCN– was 0.00050 M, the equilibrium concentration of SCN– will be___?___

A = abc.
A is absorbance, a (which should be epsilon but I can't make epsilon on this board) is the molar absorptivity constant, b is the cell length, and c is the concn in mols/L.
You know A, b, and c (c from your last post). Calculate the constant, a.
The second solution also is A = abc.
You know A, you know a, you know b, and you can calculate c. That c, in mol/L, will tell you the equilibrium concn of the complex.
Now set up an ICE chart to determine how much of the original 0.0005 SCN is used and the amount remaining.
Post your work if you get stuck. 
iam confused with the ice table could you show me because my answer .0002 is incorrect thanks.

i see what my problem is, thanks i got it.

i have a question, how did you find the length?