JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Pharmacy IV Year INSTRUMENTAL METHODS OF ANALYSIS Previous Question Paper (December 2023 / January 2024 - R17)

Beer-Lambert law states that the absorbance (A) of a monochromatic light passing through a homogeneous solution is directly proportional to the concentration (c) of the absorbing species and the path length (b) of the light through the solution. The relationship is expressed by the equation:

Where A is the absorbance, ε is the molar absorptivity (molar extinction coefficient), b is the path length in centimeters, and c is the concentration of the solution in moles per liter.

Bathochromic shift, also known as a red shift, refers to the displacement of an absorption band toward a longer wavelength (lower energy). This shift typically occurs due to the presence of auxochromes or a change in solvent polarity that stabilizes the excited state relative to the ground state.

Hypsochromic shift, also known as a blue shift, refers to the displacement of an absorption band toward a shorter wavelength (higher energy). This shift often results from the removal of conjugation or a change in solvent that stabilizes the ground state more effectively than the excited state.