In this video, we will focus on simple distillation.
Simple Distillation Basics
Simple distillation is used to obtain pure solvent from a solution of solute. For example, salt solution is made by adding salt into water. The solute is the salt that is dissolved in the water, and the water that dissolved this solid is the solvent. In order to obtain the pure solvent, which is water, from solution, which is salt water, we use the physical method, simple distillation.
In simple distillation, we allow boiling to occur. We heat up and boil the salt solution. The purpose of the boiling chips is to ensure smooth boiling. The solvent, which is water, vaporises and rises then goes into the condenser.
The thermometer, which is placed at the top of the flask, is used to measure the temperature of the vapour of the pure solvent (boiling point of the pure solvent). The bulb of the thermometer should be placed beside the side arm of the distillation flask. Do note that the bulb should not be dipped into the salt solution. If so, the thermometer will be measuring the boiling point of the salt solution, which is higher than the boiling point of the pure solvent. This is not the purpose of the thermometer in this set up.
The vapour will then flow into the condenser. Temperature in the condenser is much lower. The vapour cools down, then condenses back into liquid. The pure liquid is collected as a distillate in the receiver. If the distillate to be collected is a volatile liquid, the receiver should be placed in an ice bath. This ensures the low temperature of distillate and allows it to remain as a liquid. Do note that condenser should be sloping downwards to ensure that the pure solvent is able to flow downwards, into the receiver. Condenser has 2 tubes. Cold water flows in from the tube at the bottom, while flows out from the tube at the top. This ensures the whole condenser is filled up with cold water. This provides an efficient cooling system for the vapour.
End of experiment
At the end of the experiment, the solute remains in the distillation flask. Pure solvent is collected as distillate in the receiver.
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