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INTRODUCTION

Organic compounds differ in volatility because of the intermolecular forces present and involvedin each compound. Volatility is based on the equilibrium vapor pressure exerted by the compound at aparticular temperature. Compounds having strong intermolecular forces will definitely be more difficult

to separate. Thus, compounds having strong intermolecular forces will be less volatile. It is thereforepossible to separate compounds from each other in a mixture based on their volatility differences. Morevolatile compounds will be converted into vapor faster than those that have low volatilities. Thus, the

process of separating compounds based on their volatility differences is called distillation.

There are several types of distillation. Two of them are the simple and steam distillation, whichare used for this experiment. Simple distillation, a volatile compound is separated from a nonvolatilecompound by applying heat to the mixture. The vapor is immediately channeled into a condenser.Consequently, the distillate is not pure but rather its composition is identical to the composition of thevapors at the given temperature and pressure. That concentration follows Raoult's law. As a result,simple distillation is effective only when the liquid boiling points differ greatly or when separating liquidsfrom non-volatile solids or oils. For these cases, the vapor pressures of the components are usually

sufficiently different that the distillate may be sufficiently pure for its intended purpose.

Steam distillation is a method for distilling compounds which are heat-sensitive. Thetemperature of the steam is easier to control than the surface of a heating element, and allows a highrate of heat transfer without heating at a very high temperature. This process involves bubbling steamthrough a heated mixture of the raw material. By Raoult's law, some of the target compound will

vaporize (in accordance with its partial pressure). The vapor mixture is cooled and condensed, usuallyyielding a layer of oil and a layer of water. This is used to recover organic compound that exerts verylittle vapor pressure even at high temperatures. Water is added to increase vapor pressure so that it can

have atmospheric pressure at a lower temperature.

Thus, in this experiment, the purpose is to (1) assemble a simple and a steam distillation setup,(2) identify and recognize the significance of all parts of the setup and (3) purify a sample using simple

and steam distillation.

MATERIALS AND METHODS

The following are the apparatus used during the experiment: quick fit, pipette, hot plate andErlenmeyer flask. Meanwhile, the following are the reagents used during the experiment: impuretoluene, p-dichlorobenzene, distilled water and ice.

The experiment was divided into two parts, basically, the simple and steam distillation parts. Forthe simple distillation, the setup as shown in Figure 3.1 was assembled first. Impure toluene measuring15 ml was transferred into the pear-shaped flask. Then it was heated with the aid of the hot plate. Thedistillate was collected at different temperatures at the rate of 1 drop per second. Definitely, every timea drop of the distillate was collected, the volume was measured. (This was continued until the

temperature dramatically increased)

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