Absorption Spectra and the Beer-Lambert Law

Introduction:

Experiments 1 and 2 main aims are as follows:

• To able to use the Beer-Lambert law to explain the relationship linking concentration and absorbance of the coloured solutions methyl orange and bromophenol blue.

• To be able to rightly operate a spectrophotometer to assess the absorbance at various wavelengths

• To be able to identify the main component parts of a spectrophotometer

• To be able to draw a ‘Standard Curve’ from the data collected

• To be able to calculate the ‘percentage absorption coefficient’ for the solutions methyl orange and bromophenol blue.

Method:

The method carried out for experiments 1 and 2 were as detailed in the booklet. There was no variations from the schedule and did not encountered problems while carrying out the experiments.

Results:

Experiment 1:

|Bromophenol Blue |
|Wavelength (nm) |Absorbance |Further Readings to determine ‘ λ max’ |
|400 |0.003 |Wavelength (nm) |Absorbance |
|420 |0.009 |590 |0.979 |
|440 |0.013 |600 |0.972 |
|460 |0.019 |610 |0.595 |
|480 |0.071 | | |
|500 |0.105 | | |
|520