The hottest tray is at the bottom of the column and the coolest tray is at the top. The vapor condenses on the glass platforms (known as plates or trays) inside the column and runs back down into the liquid below, thereby refluxing the upflowing distillate vapor. As the mixture is heated and boils, vapor rises up the column. The liquid feed mixture to be distilled is placed into the round-bottomed flask along with a few anti-bumping granules, and the fractionating column is fitted into the top. The apparatus shown in the diagram represents a batch distillation as opposed to a continuous distillation. Here the distillation head and fractionating column are combined in one piece. An Erlenmeyer flask is used as a receiving flask. Laboratory apparatus using reflux to supply energy to chemical reactions. As many solvents used are flammable, direct heating with a Bunsen burner is not generally suitable, and alternatives such as a water bath, oil bath, sand bath, electric hot plate or heating mantle are employed. It includes a water bath to indirectly heat the mixture.

The diagram shows a typical reflux apparatus. the solvent's boiling point) and ambient pressure without losing large quantities of the mixture. The purpose is to thermally accelerate the reaction by conducting it at an elevated, controlled temperature (i.e. The reaction vessel is heated in order to boil the reaction mixture vapours produced from the mixture are condensed by the condenser, and return to the vessel through gravity. This vessel is connected to a water-cooled condenser, which is typically open to the atmosphere at the top. Laboratory reflux apparatus for heating a chemical reactionР”Р„ mixture of reactants and solvent is placed in a suitable vessel, such as a round bottom flask. Conversely, for a given desired separation, the more reflux is provided, the fewer theoretical plates are required. The more reflux provided for a given number of theoretical plates, the better is the column's separation of lower boiling materials from higher boiling materials. Inside the column, the downflowing reflux liquid provides cooling and condensation of the upflowing vapors thereby increasing the efficiency of the distillation column. In that context, reflux refers to the portion of the overhead liquid product from a distillation column or fractionator that is returned to the upper part of the column as shown in the schematic diagram of a typical industrial distillation column. The term reflux is very widely used in industries that utilize large-scale distillation columns and fractionators such as petroleum refineries, petrochemical and chemical plants, and natural gas processing plants.

Relux ratio