Distillation Case

The boiling point of a substance is a physical property of a substance and can be useful for characterizing that substance. The fact that different substances have different boiling points allows us to separate them. The process of heating a substance until it is vaporized, cooling the vapors, and collecting the condensed liquid is the basis of a commonly used purification technique called distillation. In this experiment, fractional distillation was introduced. Fractional distillation is the separation of a mixture into its component parts by heating the mixture and allowing to one of its components to vaporize greater than the other through the difference in boiling point. It is a technique commonly used to identify and purify organic liquids. In fractional distillation the difference in boiling of point of the components of the mixture is less than 25 oC. In this experiment, fractional distillation of mixtures of cyclohexane and toluene will be conducted. The set-up that was used in this experiment is a fractional distillation set-up which is made up of the following apparatus: 50 and 250mL round bottom flasks, 3-way connecting tube, West condenser, vacuum connecting tube, straight tube adaptor, 50mL graduated cylinder, two or three ring stands, 250mL heating mantel and voltage controller, 3-4 clamps and clamp holders, ring support, thermometer, thermometer holder, boiling chips, ice, distilling condenser and steel wool. The reagents that were used are methanol and 2-propanol. At the end of the experiment, the results were reasonable and as expected. However, there was still some error which could be improved next time.

Keywords: distillation, boiling point, separation, purify, volatile, vapor________________________________________

INTRODUCTION

Fractional distillation is used in separation and purification of compounds. It is the separation of a mixture into its component parts by heating the mixture and allowing to one of its components to vaporize greater than the other through the difference in boiling point. It is the almost the same as simple distillation. However, it is a special type of distillation. Here, the component parts boil at less than 25 oC from each other under a pressure of one atmosphere while in simple distillation; the components difference in boiling point is greater than 25 oC. In this experiment, fractional distillation of methanol and 2-propanol mixture was done. There three purposes of this experiment. First is to assemble a fractional distillation set-up. Second is to use fractional distillation technique in separating organic compounds and purifying compounds. Lastly, so that students will understand and apply the principle of fractional distillation.