# Question #8c507

Jul 31, 2017

#### Answer:

Rearrangement of Beer's law

#### Explanation:

Beer's law states that you can determine the absorbance (A) with three factors: molar absorptivity ($\epsilon$), path length (b), and concentration (c). Absorbance has no units. Path length is usually 1 cm. The molar absorptivity is measured in $L \cdot m o {l}^{-} 1 \cdot c {m}^{-} 1$. Concentration is in $m o l \cdot {L}^{-} 1$.

$A = \epsilon b c$

If you rearrange the equation, you can solve for concentration.

$c = \frac{A}{\epsilon b}$