Lambert Beer law Numerical || lambert Beer law || Absorbance and Transmittance Numerical
Understanding Lambert's Beer Law: Numerical Problem Solving
Introduction to Lambert's Beer Law
- Dr. Anjari Saxena welcomes learners and references a previous video on Lambert's Beer Law, indicating that a numerical problem related to it was solved.
- The formula for Lambert's Beer Law is introduced: A = epsilon c x , where:
- A = Absorbance
- epsilon = Molar absorptivity
- c = Concentration
- x = Thickness or path length of the sample.
Overview of the Current Numerical Problem
- The current numerical problem involves provided transmittance values, from which absorbance will be calculated.
- Key relationships are recalled:
- Transmittance ( T ) is defined as T = I/I_0 .
- Absorbance ( A ) can be derived using the equation A = -log(T) .
Given Data for Calculation
- Specific data provided includes:
- Path length ( x ) of 1 cm.
- Absorption of incident light at a rate of 20%.
- Molar absorptivity ( epsilon ) value of 2.0.
Steps to Solve for Concentration
- To find concentration, we note that if the incident radiation intensity is considered as 100%, then with an absorption rate of 20%, transmittance would be at 80%.
- Using the relationship between absorbance and transmittance, we calculate absorbance:
- Formula used: A = -log(T)
- Resulting in an absorbance value of approximately A = 0.096.
Final Calculation and Conclusion
- With known values for absorbance and path length, concentration can now be calculated using rearranged Lambert’s law.