[jackrobertwilliamson]

I have this problem that is a bit hard to figure out.  It goes as follows:

An 8.64 ppm (1 ppm = 1 mg/L) solution of FeNCS^2+ has a trasmittance of 0.295 when measured in a 1.00 cm cell at 580 nm.  Calculate the extinction coefficient at this wavelength.

Now I may have the right solution to this, but I'm not totally sure, as it is a bit beyond what the lab book explicitly goes into.

So here is the solution I have. 

1 mol FeNCS is 113.93 g/L, thus the molarity of the solution is 0.00864g/L/113.93g/L = 0.00008mol/L

Absorbance = 2-log(0.295/1.00) = 0.530

A = abc, where a is the extinction coefficient, b is the solution path length, and c is concentration, thus a = A/bc

So, a = 0.530/1cm*0.00008mol/L = 6625 L/mol-cm

Is this answer correct, and if not, where did I go wrong? 

Thanks.

[chenbeier]

Sounds good .