Question

A solution of a compound in ethanol shows an absorbance of 0.58 at 236 nm in a cell with a 1-cm light path. Its molar absorptivity in ethanol at that wavelength is 12,600 M−1cm−1. What is the concentration of the compound? Express your answer to two significant figures and include the appropriate units.

Answer 1

Answer:

C = 4.60x10⁻⁵ M

Explanation:

The concentration of the compound can be calculated using Beer-Lambert Law:

$A = \epsilon*C*l$

Where:

A: is the absorbance of the ethanol = 0.58  

ε: is the molar absorptivity of the ethanol = 12600 M⁻¹cm⁻¹

C: is the concentration of the compound =?

l: is the optical path length = 1 cm

Hence, the concentration of the compound is:

$C = \frac{A}{\epsilon*l} = \frac{0.58}{12600 M^{-1}cm^{-1}*1 cm} = 4.60 \cdot 10^{-5} M$

Therefore, the concentration of the compound is 4.60x10⁻⁵ M.

I hope it helps you!