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Absorbance Equation:
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The absorbance equation (Beer-Lambert Law) relates the concentration of a solution to its absorbance, molar absorptivity, and path length. It is a fundamental principle in spectrophotometry and analytical chemistry for determining unknown concentrations.
The calculator uses the absorbance equation:
Where:
Explanation: The equation demonstrates that concentration is directly proportional to absorbance and inversely proportional to both molar absorptivity and path length.
Details: Accurate concentration determination is essential in chemical analysis, pharmaceutical development, environmental monitoring, and various research applications where precise quantification of substances is required.
Tips: Enter absorbance (unitless), molar absorptivity in L/mol cm, and path length in cm. All values must be valid (absorbance ≥ 0, molar absorptivity > 0, path length > 0).
Q1: What is the Beer-Lambert Law?
A: The Beer-Lambert Law states that absorbance is directly proportional to the concentration of the absorbing species and the path length of the light through the sample.
Q2: What are typical values for molar absorptivity?
A: Molar absorptivity values range from near 0 to over 100,000 L/mol cm, depending on the specific compound and wavelength used.
Q3: What is the standard path length used in spectrophotometry?
A: The most common path length is 1.0 cm, though other sizes (0.1 cm, 1.5 cm, etc.) are also used depending on the application.
Q4: Are there limitations to this equation?
A: The equation assumes dilute solutions, monochromatic light, and no chemical interactions that might affect absorbance. It may not be accurate at very high concentrations.
Q5: What is the linear range for absorbance measurements?
A: Typically, absorbance values between 0.1 and 1.0 provide the most accurate results, though modern instruments can often handle a wider range.