What is the purpose of the boiling point/refractive index experiment?

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Properties determined by the two experiments may be used for the purpose of the identification of an unknown liquid. Identification of matter can be achieved through observing their chemical or physical properties. Physical reactions are a better mode of identification because they don’t alter the substance under observation. Chemical reactions alter the chemical composition of a substance thus resulting in a change of the substance under study.

The boiling point refers to temperature at which a substance’s vapor pressure is equal to the atmospheric pressure around the sample.

The refractive index refers to the ratio of light’s velocity going through a sample compared to the velocity of light going through a vacuum.

Boiling point and refractive index are physical properties and can be used in the identification of unknown pure samples. It is important for the sample to be pure because impurities in the sample will alter its properties readings. Pure water, for instance, has a boiling point of 100 degrees Celsius and a refractive index of 1.3330. Thus, an unknown liquid exhibiting such properties may point to water. Further, determining other properties such as density may help confirm if indeed the sample is water.

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