Solve the Beer–Lambert law A = εlc for absorbance, molar absorptivity, path length or concentration — leave the one you want blank.
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From the article Beer–Lambert Law A = εlc — Absorbance and Concentration.
Question: A dye has ε = 5500 L mol⁻¹ cm⁻¹ at 520 nm. What is the absorbance of a 2.4 × 10⁻⁵ mol L⁻¹ solution in a 1.00 cm cuvette?
A = ε l c
A = 5500 × 1.00 × 2.4 × 10⁻⁵
A = 5500 × 2.4 × 10⁻⁵ = 13 200 × 10⁻⁵
A = 0.132
Check: A is small, so most light passes through — T = 10⁻⁰·¹³² ≈ 0.74, i.e. about 74% of the light gets through. A pale solution. That is consistent.
Worked in full in Beer–Lambert Law A = εlc — Absorbance and Concentration.
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