Chapter 15, Problem 15.3YT

Interpretation Introduction

Interpretation:

It is to be determined which wavelength of light corresponds to photons with greater energy: $\text{375 nm}$ or $\text{530 nm}$.

Concept introduction:

The band in the UV-vis spectrum at which absorbance is a local maximum which corresponds to the ${\text{λ}}_{\text{max}}$ (lambda-max) shows the absorbance at the maximum wavelength. Electromagnetic radiations have dual nature, particle as well as wave. When it behaves as a particle, then the radiation exists as photons. Each photon possesses characteristic energy that depends only on its frequency (or wavelength) and is given by the Plank’s equation: ${\text{E}}_{\text{photon}}{\text{= hυ}}_{\text{photon}}{\text{= hc/λ}}_{\text{photon}}$, where h: Plank’s constant (value is $\text{6}{\text{.626×10}}^{\text{-34}}\text{J}\text{.s}$), c: speed of light, universal constant (value is $\text{2}{\text{.9979 × 10}}^{\text{8}}\text{m/s}$), and ν is the frequency of the corresponding light. In UV–vis spectroscopy, the energy of a photon is directly proportional to the frequency of the light and consequently inversely proportional to the wavelength of light. So the photon’s energy increases with a decrease in the wavelength of light.