Distillation Lab Report

Title: Distillation Objective: The objective of this lab is to study distillation and examine the relationship between volume and temperature during a simple distillation procedure. Introduction: Distillation is a common method for purifying liquids and can be used to determine their boiling points. On one hand, simple distillation is used to purify liquid mixtures by separating one liquid component either from nonvolatile substances or from another liquid that differs in boiling point by at least 75°C. On the other, fractional distillation differs from simple distillation in that a fractionating column is placed between the distilling flask and the condenser. This fractionating column allows for successive condensations and distillations and produces a much better separation between liquids with boiling points closer than 75°C. A pure liquid has a constant boiling point. A change in boiling point during distillation is an indication of impurity. The converse proposition, however, is not always true; that is, constancy of a boiling point does not necessarily mean that the liquid consists of only one compound. Reactions/Schemes/Mechanisms Rault’s Laws: Pc = 5 P° cNc Materials: a simple distillation apparatus thermometer 40 mL of 50:50 mixture of toluene methylenedichloride a boiling chip water faucet Apparatus: Simple Distillation Apparatus: Table of Physical Constants: Name Structure MW MF (g/mol) BP/MP Density (degrees (kg/m³) Solubility Celsius) Cyclohexane 84.16 C6H12 81/6.5 779 Immiscible in water; soluble in ether, alcohol and acetone Toluene 92.14 C7H8 111/-95 867 In water: 0.52 g/L Procedure: Procedure Observations 1) Assemble apparatus 2) Add 40 mL of 50:50 mixture of Tulane methylanedichloride 3) Add boiling chips 4) Heat and collect. Record temp and volume at regular intervals (every minute) until you reach 20mL helps boils the mixture As the temperature began to increase the valve began to fog up Temperature increased very quickly Took a while to reach 5 mL but quicker to reach 10+ mL’s Precautions: Cyclohexane and toluene are flammable; make sure the distilling apparatus is tight. Do not add a boiling chip to a hot liquid. It may boil over. Waste Disposal: Dispose of cyclohexane and toluene in the waste container provided. Do not pour them down the drain. Results and Discussion: Volume (mL) 0 5 10 15 20 Temperature (°C) 25° 49° 52° 60° 57° Distillation is a physical process used to separate chemicals from a mixture by the difference in how easily they vaporize. As the mixture of toluene methylenedichloride is heated the temperature rises until reaching the temperature of the lowest boiling substance in the mixture, while the other components of the mixture remain in their original phase. The resultant hot vapor passes into a condenser and is converted to a liquid, which is collected in a graduated cylinder. The other components of the mixture will remain in their original phase until the most volatile substance has boiled off, and only when the temperature rises again does the second component of the mixture reach its boiling point. The boiling point of a substance, determined by distillation, is a helpful physical property used to characterize pure compounds. Conclusion: Distillation is an effective method of separating the constituent parts of a mixture. As outlined in the above table and graph the temperature spiked when the volumed first increased to 5 mL, they increased at a slower pace from 10-15 mL. Interestingly, the temperature dipped at the final, volume of 20 mL. In this experiment only simple distillation was practiced. In simple distillation it is easier when the two components have a larger difference in boiling points. The only error in this lab could have been the use of the sand bed instead of a hot plate. The sand bed took much longer to heat the mixture compared to another group utilizing the hot plate.