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 :

$A=\epsilon \times C\times l$

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

$\frac{A_1}{A_2}=\frac{C_1}{C_2}$

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:

$\frac{0.350}{0.420}=\frac{0.135}{C_2}$

$C_2=0.162M$

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