Concentration from absorbance

Worked example

Find c from A = 1.07, ε = 10000 dm³ mol⁻¹ cm⁻¹ and a path length of 1.0 cm.

1. 1. Beer–Lambert law: solve for c

   $c = \dfrac{A}{\varepsilon l}$

   = 1.070 × 10⁻⁴ mol dm⁻³

Answer: c = 1.07 × 10⁻⁴ mol dm⁻³

Method

c = A/(εl). Keep ε and l in matching length units (cm here).

Formulas used

• Beer–Lambert law

  $A = \varepsilon lc$

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