Question

If a 0.0121 M solution of a certain analyte exhibits 48.9% T at a wavelength of 280 nm, what will the percent transmittance be for a 0.0280 M solution of the same analyte? Assume the pathlengths for each measurement are equal.

Answer 1

The Beer-Lambert law (or Beer's law) is the linear relationship between absorbance and concentration of an absorbing species.

According to this law:

The equation is: A = ebc.

Here e = molar absorbtivity, in L/mol *cm

b = cell path length in cm,

and c = concentration in moles/liter or M

and

A = log (1/T)

Here T = 48.9%

48.9% T corresponds to Abs = log[100/48.9] = 0.311

From Beer’s Law for same εb
Abs1/Abs2 = c1/c2 Abs1

= (c1/c2)Abs2 = [(0.0280/0.0121)](0.311) = 0.720
%T log[Io/I] = 0.720

Taking anti log:

5.25 = 100/T

T = 100/5.25

= 19.05%