Question

A 0.26 M solution of compound "B" is measured in a 1.00 cm path length cuvette at a wavelength of 565 nm. The percentage of light transmitted through the cell is 44%. What is the molar absorbance of this sample at 565 nm (in units of mol-1 cm-1)?

Answer 1

Explanation:

Given data:

Molar concentration(C) = 0.26 M. path length (b) = 1.00 cm. %T = 44.

Where absorbance (A) and Molar absorbance (E) are unknown.

Solution:

This problem is related with Lambert beers law. We use absorbance and transmittance relation in order get absorbance.

To calculate molar absorbance we simply use A = ebc

Where e = molar absorbance (absorptivity)

Calculation of absorbance:

A= -log (%T)

= 2-log (T)

= 2-log (44)

= 2-1.6435

= 0.3565

Absorbance = 0.3565

Calculation of molar absorbance :

E= A/bC

Lets plug given values,

                =0.3565/ (1.00 x 0.26)

= 1.3712 M^-1cm^-1

Molar absorbance (E epsilon) of the given solution at 565 nm is 1.3712 M^-1cm^-1.