Question

If a solution has an absorbance of 0.100 in a 1.00 cm pathlength cuvette, what would the absorbance be in a cuvette of 0.55 cm pathlength cell?

Answer 1

According to Beer Lambert's law A = a b c

where

A = measured absorbance

a = wavelength-dependent absorptivity coefficient

b = path length

c = analyte concentration

Since the solute is the same a & c will remains the same so A is proportional to b

So A / A' = b / b'

Where

A = initial absorbance = 0.100

A' = final absorbance = ?

b = initial path length = 1.00 cm

b' = final path length = 0.55 cm

Plug the values we get

A' = (Ab') / b

    = ( 0.100x0.55) / 1.00

    = 0.055

Therefore the absorbance is 0.055