Question

Discuss the relationship between color and lambda max. How it is related to the spectrophotometric analyte method that we use in lab (one paragraph)

Answer 1

UV-Vis spectroscopy is done in the UV and visible region (200-800 nm). when irradiated with light, the molecule, absorb some part of the light and transmit some part. Whatever is the color of the transmitted light will be the color of the compound. lamda max is the wavelength where the absorbance is largest. We will see the complementary color of the color which is indicated by the lambda max. For example is the molecule has a lambda max 700nm (red color), the observed color will be green. Similarly, if it absorb 400nm (violet) , then it will look yellow.

Every molecule has a specific lambda max value at which it has a characteristic molar extinction coefficient value. In fact the UV-Vis spectra of any molecule is its characteristic property. Also, absorbance depnds on the concentration. Thus if you know the absorbance value you can find out the concentration and vice versa.