Which method is used to separate crude oil into its fractions?

The method used to separate crude oil into its fractions is fractional distillation. This technique takes advantage of the different boiling points of the various components present in crude oil. During fractional distillation, crude oil is heated in a distillation column, and as the temperature rises, different hydrocarbons vaporize at different temperatures. Each fraction can then be condensed and collected separately based on these boiling points.

In contrast, filtration is unsuitable for separating crude oil because this method is effective for separating solids from liquids or larger particles from smaller ones, which is not applicable to the liquid mixtures in crude oil. Centrifugation involves spinning a mixture at high speeds to separate components based on density and is more commonly used in laboratory settings for cell separation or purification processes rather than for hydrocarbon mixtures like crude oil. Crystallization is a technique used to purify solid compounds by forming crystals from a solution, which does not apply to the separation of liquid fractions in crude oil. Thus, fractional distillation is the most appropriate method for this process.