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 0.520. If a trial's absorbance is measured to be 0.275 and its initial concentration of SCN– was 0.00060 M, the equilibrium concentration of SCN– will be... ?
chem - DrBob222, Sunday, April 11, 2010 at 2:49pm
I am confused about the "initial" concn. I understand that it is 6 x 10^-4 M; however, nothing in the problem sets it up. The concn of SCN^- that is MEASURED (is that the same as the initial concn?) is done this way.
Concn of standard SCN^- = 0.002 M x 1/10 = 2 x 10^-4 M (STANDARD).
Sample = 2 x 10^-4 M x (0.275/0.520) = ?? M