Question

Data has been collected to show that at a given wavelength in a 1 cm pathlength cell, Beer's Law for the absorbance of Co2 is linear. If a 0.135 M solution of Co2 has an absorbance of 0.350, what is the concentration of a solution with an absorbance of 0.420?

Answer 1

Answer : The concentration of a solution with an absorbance of 0.420 is, 0.162 M

Explanation :

Using Beer-Lambert's law :

`A=\epsilon * C* l`

As per question, at constant path-length there is a direct relation between absorbance and concentration.

`(A_1)/(A_2)=(C_1)/(C_2)`

where,

A = absorbance of solution

C = concentration of solution

l = path length

`A_1` = initial absorbance = 0.350

`A_2` = final absorbance = 0.420

`C_1` = initial concentration = 0.135 M

`C_2` = final concentration = ?

Now put all the given value in the above relation, we get:

`(0.350)/(0.420)=(0.135)/(C_2)`

`C_2=0.162M`

Thus, the concentration of a solution with an absorbance of 0.420 is, 0.162 M