Derivation of Beer Lambert law: Spectroscopy/Analytical techniques/Photochemistry 

Statement and derivation of Beer-Lambert's law is explained in detail with illustrations. Mentions the limitations of Beer-Lambert's law. Applications of Beer-Lambert's law.The Beer-Lambert law, also known as Beer's law, the Lambert-Beer law, or the Beer-Lambert-Bouguer law.
Beer- Lambert’s Law
You will be able to
state and derive Beer-Lambert’s law
list out the limitations of this law.
discuss the applications of this law.
Note: Solve problems based on this law in the next session.
When a monochromatic light is passed through a solution containing the absorbing substance, the decrease in the intensity of light with path length is proportional to the concentration of the solution and the intensity of light.
Beer-Lambert law : Derivation
Integrating on both sides between the limits
I=Io when l=0 and I=I when l=l
Molar extinction coefficient
or
Molar absorption coefficient
e is a function of wavelength
It is suitable only for monochromatic light.
It is not suitable for higher concentration as there is deviation in e.
Scattering of light due to presence of particulate matter.
If the sample is fluorescent or phosphorescent.
Applications of Beer-Lambert law
To determine the unknown concentration of known solution
Ak -Absorbance of known solution
Au -Absorbance of unknown solution
ck -concentration of known solution
cu -Absorbance of unknown solution