Beer and Lambet law
Tittle : Absorption Spectra and the Beer-Lambert Law. ɛ Purpose : Understanding of Beer –Lambert Law
Introduction : When light passes through the colour solution , the molecules of the solution absorb the quantity of light at a particular wavelength . The amount of light which is absorbed by solution depend on two things.
1. The length of the pathway of light
2.Concentration of colour solution.
These are all explained by the Beer-Lambert Law.
Absorbance (A) = ɛcl A= Absorbance ɛ = molar absorption coefficient (Depend on unit concentration ) c = concentration of colour solution. l = length of the light path.
In here two experiments were carried out to clarify the relationship between concentration and absorbance in different wavelengths. According to the Beer-Lambert Law absorbance is directly proportional to the concentration of the colour solution or compound.
Hypothesis : Able to determine the molarity of unknown solution through the Beer-Lambert law.
Material : spectrometer,cuvettes, test tubes, water,Bromophenol blue(10mg/l),Methyle orange (10mg/l).
Method : beginning of the experiment spectrometer was prepared for the experiments.It was confirmed that cuvettes were filled with a solution not more than than 2/3 full. Cuvettes were left in the compartment with clear side facing left and right.
Experiment 1
Absorbance of Bromophenol Blue and Methyle Orange was measured in different wavelength between 400nm to 700 ,It was measured every 20 nm intervals. (Distilled water measurement was taken as zero.).λmax was identified for the two dyes.further reading was made to get pricise λ max in higher absobance.
Table 1
BromoPhenol Blue.
Absorbance
Further reading to determine ' λ max'
Wavelength (nm)
Wavelength (nm)
Absorbance
400
0.101
590
0.874
420
0.047
592
0.938
440
0.038
608
0.869
460
Introduction : When light passes through the colour solution , the molecules of the solution absorb the quantity of light at a particular wavelength . The amount of light which is absorbed by solution depend on two things.
1. The length of the pathway of light
2.Concentration of colour solution.
These are all explained by the Beer-Lambert Law.
Absorbance (A) = ɛcl A= Absorbance ɛ = molar absorption coefficient (Depend on unit concentration ) c = concentration of colour solution. l = length of the light path.
In here two experiments were carried out to clarify the relationship between concentration and absorbance in different wavelengths. According to the Beer-Lambert Law absorbance is directly proportional to the concentration of the colour solution or compound.
Hypothesis : Able to determine the molarity of unknown solution through the Beer-Lambert law.
Material : spectrometer,cuvettes, test tubes, water,Bromophenol blue(10mg/l),Methyle orange (10mg/l).
Method : beginning of the experiment spectrometer was prepared for the experiments.It was confirmed that cuvettes were filled with a solution not more than than 2/3 full. Cuvettes were left in the compartment with clear side facing left and right.
Experiment 1
Absorbance of Bromophenol Blue and Methyle Orange was measured in different wavelength between 400nm to 700 ,It was measured every 20 nm intervals. (Distilled water measurement was taken as zero.).λmax was identified for the two dyes.further reading was made to get pricise λ max in higher absobance.
Table 1
BromoPhenol Blue.
Absorbance
Further reading to determine ' λ max'
Wavelength (nm)
Wavelength (nm)
Absorbance
400
0.101
590
0.874
420
0.047
592
0.938
440
0.038
608
0.869
460