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

C = 4.60x10⁻⁵ M

Step-by-step 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 = (A)/(\epsilon*l) = (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!