Question

Describe the different causes for deviations from Beer's law. Why is a calibration curve likely to be linear over a wider range of concentration at the wavelength of maximum absorption compared to a wavelength on the shoulder of the absorption curve?

Answer 1

0 According to Beer'slaw, the intensity of a beam of monoichromatic radiation decreases exponentially with increase in the thickness and concentration of the absorbing medium A = 10 (4)= edc A= 108()- absorbance 1. Einitial intensity of incident radiation I = final intensity of incident radiation s=absorption coefficient b=path length c=concentration of absorbing medium plot of A vesus cis a straight line at higher concentrations, ions of electrolytic solute are capable of disturbing the charge distribution of neighbours.interionic interactions canseverly alter the ability of the solute to absorb a given wavelength of theincident radiation thus plots of A versus c are nolonger be linear hence there will be severe deviations from Beer's law at higher concentrations At higher concentrations, refractive index of the solution also changes which causes the severe deviations from Beer'slaw.

(2) Answer:

The calibration curve is expected to be linear in order to get minimal error values. More of error values will leads away from the linearity of the curve.