why does ethanol evaporate faster than water

Answer 1: Thank you for the question. Rubbing alcohol
consists mainly of ethanol or isopropanol. Ethanol and isopropanol boil at a lower temperature than water, which generally means that they will evaporate quicker than water. The boiling temperature is largely determined by attractive interactions between the liquid molecules. The attraction between 2 ethanol molecules is weaker than the attraction between 2 water molecules, which means that the water molecules do not want to be separated like they would in a vapor or gas upon evaporation.

Water molecules attract each other strongly because each molecule participates in 4 attractive "hydrogen bonds," which are bonds between the hydrogen of one water molecule and the oxygen of another water molecule.

Ethanol and isopropanol each only participate in 2 hydrogen bonds. Click to return to the search form. Distillation is a process that can be used to separate a pure liquid from a mixture of liquids. It works when the liquids have different boiling points. Distillation is commonly used to separate ethanol (the alcohol in alcoholic drinks) from water.

The mixture is heated in a flask. Ethanol has a lower boiling point than water so it evaporates first. The ethanol vapour is then cooled and condensed inside the condenser to form a pure liquid. The thermometer shows the boiling point of the pure ethanol liquid. When all the ethanol has evaporated from the solution, the temperature rises and the water evaporates.

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