The Separation of a Liquid Mixture by Simple Distillation

The Separation of a Liquid Mixture by Simple Distillation

Organic Chem. I Lab 2102. 11 & 12

September 19, 2013

Objective

The purpose of doing this experiment is to separate two miscible liquids samples of cyclohexane and toluene using simple distillation. The objectives will be to record boiling range and volumes (mL) of distillates that are attained during the process of distillation.

Background

Distillation is a frequently used technique for separating mixtures based on differences in the boiling points of components in the mixture. The product obtained by distillation, is termed the distillate. Volatility is the property of changing readily from a solid or liquid to a vapor or the tendency of a substance to vaporize. It is directly related to a compounds vapor pressure. A compound with higher vapor pressure vaporizes sooner than a compound with a lower vapor pressure. In the course of distillation the substances are heated to a boiling point in a glass container known as the pot. A condenser that is cooled by flowing water is used to cool the vapors produced as they re-liquefy and are collected in a separate container known as the receiver. Evaporation is a type of vaporization of a liquid which occurs at temperatures below the boiling point that take place from the surface of a liquid, into a gaseous stage of only the molecules on the liquid surface. Equilibrium vapor pressure is obtained once the equilibrium is reached between molecules that are entering and leaving the liquid state and vapor state. This pressure is dependent on the physical characteristics of substances and temperature increasing with time. Another type of vaporization is boiling. The boiling point occurs in the entire mass of sample liquid. When the liquid is heated to its boiling the external pressure and vapor pressure are equal. Once boiling point is reached bubbles come up to the surface of the liquid and escape producing a frenzied motion that is associated with the boiling liquid. This is a very import process in everyday use. In many third world countries the act of boiling water can save a life by killing harmful bacteria and parasites that would otherwise infect the person drinking it.

Procedure

The equipment used were boiling chips, copper metal sponge, electric flask heater, 50 ml graduated cylinder, standard taper glassware including condenser, adapter and rubber tubing, distilling head, 100 ml round-bottom flask, 10 to 260 C thermometer with adapter, 2 support rings, 2 support stands, 2 utility clamps, wire gauze, ceramic center. A caution throughout the experiment Cyclohexane is flammable and irritating. Toluene is flammable and toxic. Boiling chips must not be added