Group A – Determination of Lambda Max for the Iron 

1.  Acquire 3 cuvettes from the stockroom: 
One for the 0.5M HNO3 blank,
one for the known Fe(SCN)3 solution and
one with unknown Fe(SCN)3 solution.
2.  Set the spectrophotometer at 400 nm. 
Zero the spectrophotometer.
3.  Place the cuvette with the 0.5M HNO3 (the reference
solution or blank) in the holder and adjust the light
control knob to 100%.  Remove the cuvette.
4.  Place the cuvette with the unknown solution Fe(SCN)3
in the holder.
5.  Record the % Transmittance on Datasheet 1.
6.  Change to the next wavelength and repeat steps 2-5.
7.  Calculate the Absorbance for each of the
% Transmittance values.
8.  Record the wavelength that corresponds to the
Maximum Absorbance.
9.  Use this ÒMaximum AbsorbanceÓ wavelength for Part B.