Briefly explain Fractional distillation
Fractional distillation is a separation process that is used to divide a mixture into its individual components or fractions, based on differences in their boiling points. It is particularly useful for separating liquids that have boiling points that are relatively close to each other.
The process involves the following steps:
1. The mixture is heated in a distillation column or a fractionating column, which is packed with trays or plates, or filled with packing material to provide a large surface area for vapor-liquid contact.
2. As the mixture heats up, the component with the lowest boiling point vaporizes first. It rises up the column, which is typically cooler at the top than at the bottom.
3. The vapor cools as it rises through the trays or packing and may condense back into a liquid. As it does so, it heats and vaporizes again, a process known as reflux.
4. Reflux helps promote the exchange between rising vapors (which become progressively richer in the lower-boiling component) and the descending liquid (which becomes progressively richer in the higher-boiling component).
5. These repeated vaporization and condensation cycles allow for a gradual separation of components based on volatility, with the lowest boiling substance moving toward the top of the column.
6. The separated vapors at different levels of the column can be withdrawn through side outlets. The vapor at the very top, which is the most enriched in the lowest boiling component, eventually reaches the condenser, where it is cooled and condensed into a liquid. This liquid can then be collected as the distillate.
7. The process continues until the desired level of purity is achieved for each component being separated.
Fractional distillation is widely used in various industries, such as petroleum refining, chemical production, and the manufacture of alcoholic beverages, to name a few.