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](https://tex.z-dn.net/?f=A%3D%5Cepsilon%20%5Ctimes%20C%5Ctimes%20l)
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}](https://tex.z-dn.net/?f=%5Cfrac%7BA_1%7D%7BA_2%7D%3D%5Cfrac%7BC_1%7D%7BC_2%7D)
where,
A = absorbance of solution
C = concentration of solution
l = path length
= initial absorbance = 0.350
= final absorbance = 0.420
= initial concentration = 0.135 M
= final concentration = ?
Now put all the given value in the above relation, we get:
![\frac{0.350}{0.420}=\frac{0.135}{C_2}](https://tex.z-dn.net/?f=%5Cfrac%7B0.350%7D%7B0.420%7D%3D%5Cfrac%7B0.135%7D%7BC_2%7D)
![C_2=0.162M](https://tex.z-dn.net/?f=C_2%3D0.162M)
Thus, the concentration of a solution with an absorbance of 0.420 is, 0.162 M