Question

I'm doing an assignment on Spectrophotometry but can't find an answer to this:
State a suitable colour and wavelength of light (in nanometers) to measure absorbance by bromine.
Can someone help me please?? :/

Answer 1

Bromine gas appears red-brown, which means when white light passes through a sample of bromine, the red and orange wavelengths pass through. Everything else is absorbed. The more bromine there is, the more light is absorbed, so the less light that makes it all the way through the sample.

When choosing a color for spectroscopy, we always want to choose a color that we KNOW will be absorbed by the sample. Knowing bromine is red means that wavelengths of blue and green are absorbed.