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Molarity From Absorbance Formula:
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The Beer-Lambert law relates the absorption of light to the properties of the material through which the light is traveling. This calculator uses the equation to determine molarity from absorbance measurements for liquid samples.
The calculator uses the Beer-Lambert law equation:
Where:
Explanation: The equation calculates the concentration of a solution based on how much light it absorbs, considering the specific absorption characteristics of the substance and the distance the light travels through the solution.
Details: Accurate molarity determination is crucial for quantitative analysis in chemistry, biochemistry, and environmental science. It helps in determining solution concentrations for experiments, quality control, and research applications.
Tips: Enter absorbance (unitless), molar absorptivity in M⁻¹ cm⁻¹, 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 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.
Q2: What are typical values for molar absorptivity?
A: Molar absorptivity values vary widely depending on the substance and wavelength, ranging from near 0 to over 100,000 M⁻¹ cm⁻¹ for highly absorbing compounds.
Q3: What is the standard path length for absorbance measurements?
A: The most common path length is 1.0 cm, though cuvettes with different path lengths (0.1 cm to 10 cm) are available for various applications.
Q4: Are there limitations to the Beer-Lambert law?
A: Yes, the law assumes monochromatic light, dilute solutions, and that absorbance is solely due to the compound of interest without interactions between molecules.
Q5: Can this calculator be used for any wavelength?
A: Yes, but you must use the molar absorptivity value specific to the wavelength of measurement for accurate results.