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Beer-Lambert Law:
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The Beer-Lambert Law describes the relationship between the absorption of light and the properties of the material through which the light is traveling. It states that absorbance is directly proportional to the concentration of the absorbing species and the path length of the light through the material.
The calculator uses the Beer-Lambert Law equation:
Where:
Explanation: The law states that the amount of light absorbed by a solution is proportional to the concentration of the absorbing species and the distance the light travels through the solution.
Details: Absorbance measurements are crucial in analytical chemistry for quantitative analysis, particularly in spectrophotometry for determining concentrations of substances in solution.
Tips: Enter molar absorptivity in L/mol·cm, concentration in mol/L, and path length in cm. All values must be positive numbers greater than zero.
Q1: What is the range of valid absorbance values?
A: Typically 0.1 to 2.0 for accurate measurements. Values above 2.0 may not follow the Beer-Lambert Law due to detector limitations.
Q2: Why is absorbance unitless?
A: Absorbance is defined as the logarithm of the ratio of incident to transmitted light intensity, making it a dimensionless quantity.
Q3: What affects molar absorptivity?
A: Molar absorptivity depends on the substance, solvent, temperature, and wavelength of light used for measurement.
Q4: When does Beer-Lambert Law not apply?
A: The law may not hold at very high concentrations, with fluorescent compounds, or when chemical associations occur between molecules.
Q5: How is transmittance related to absorbance?
A: Absorbance = -log₁₀(Transmittance), where transmittance is the fraction of light that passes through the sample.