How can spectroscopy be used to assess purity?

Spectroscopy can be used to assess purity by identifying and quantifying the different substances present in a sample.

Spectroscopy is a powerful tool in analytical chemistry that allows scientists to determine the composition of a sample by analysing the way it interacts with light. Different substances absorb or emit light at different wavelengths, creating a unique 'spectral fingerprint' that can be used to identify them. By comparing the spectrum of a sample to known spectra of pure substances, it is possible to determine what substances are present in the sample and in what proportions.

In the context of assessing purity, spectroscopy can be used to detect impurities in a sample. If a sample is pure, its spectrum should match exactly with the spectrum of the pure substance. Any deviations from this could indicate the presence of impurities. For example, if a sample is supposed to be pure ethanol, but its spectrum shows peaks at wavelengths where ethanol does not absorb light, this could suggest that there are other substances present.

Furthermore, spectroscopy can also provide quantitative information about the purity of a sample. The intensity of the peaks in a spectrum is proportional to the concentration of the substance that produces them. Therefore, by measuring the intensity of the peaks, it is possible to estimate the concentration of each substance in the sample. This can be used to calculate the percentage purity of the sample.

In summary, spectroscopy is a valuable tool for assessing purity as it can identify and quantify the different substances present in a sample. It is a non-destructive technique, meaning the sample is not altered or destroyed during the analysis, which is a significant advantage in many applications.