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Beer-Lambert Law:
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The Beer-Lambert law (also known as Beer's law) describes the relationship between the absorption of light and the properties of the material through which the light is traveling. It states that the absorbance of a solution is directly proportional to the concentration of the absorbing species and the path length of the light through the solution.
The calculator uses the Beer-Lambert law equation:
Where:
Explanation: This equation allows calculation of unknown concentration when absorbance, molar absorptivity, and path length are known.
Details: Accurate concentration determination is crucial in analytical chemistry, biochemistry, pharmaceutical analysis, environmental monitoring, and quality control processes across various industries.
Tips: Enter absorbance (unitless), molar absorptivity in L/mol·cm, and path length in cm. All values must be positive numbers greater than zero for accurate calculation.
Q1: What is the valid range for absorbance values?
A: For accurate measurements, absorbance values should typically be between 0.1 and 1.0. Values outside this range may suffer from significant measurement errors.
Q2: How do I determine molar absorptivity?
A: Molar absorptivity is typically determined experimentally by measuring absorbance of solutions with known concentrations and using the Beer-Lambert law.
Q3: What are common path lengths used in spectrophotometry?
A: Standard cuvettes typically have 1 cm path lengths, though other sizes (0.5 cm, 2 cm, etc.) are also available for different applications.
Q4: When does the Beer-Lambert law not apply?
A: The law may not hold at very high concentrations, with polychromatic light, in scattering solutions, or when chemical associations occur between molecules.
Q5: Can this calculator be used for any absorbing species?
A: Yes, as long as you have the correct molar absorptivity value for the specific compound and wavelength being measured.