Question

A lab group obtained the following equation for their calibration curve for a series of dilutions: y = 17.711x + 0.104. They measure the absorbance of a solution of unknown concentration and found that absorbance to be 0.349. What is the concentration of their unknown solution (in Molarity)?

Answer 1

From the Beer's law,

Absorbance=eCl+constant

where e=molar absorbance constant, C=concentration and l=path length

Absorbance=(el) Concentration + Constant

GivenThe equation from calibration curve is

y=17.711x + 0.104

where y=absorbance and x=concentration.

Given absorbance=0.349 then concentration=?

0.349 = 17.711 (concentration) + 0.104

Concentration=(0.349-0.104)/17.711=0.0138 M

Concentration of unknown solution, C=0.0138 M.

Please let me know if you have any doubt.