What is Simple Distillation?
simple distillation is a separation technique or type of distillation in chemistry that is useful for purifying liquids in laboratories. where nonvolatile impurities are removed by using this process. It allows the separation of volatile components from non-volatile components present in different liquids. immediate vapors are produced and then condensed if distillate is not pure. at given temperature and pressure.
mixtures of miscible liquids are separated by using this technique. these liquids should have <150 ° C at atmospheric pressure and then risen about at least 25 ° C.
Therefore, it takes advantage of the boiling point properties of liquid mixtures. This process also serves to separate two liquids that are in a solution.
the distillation process obeys Raoult’s law.
Simple Distillation Apparatus
for the setup, we need some Apparatus such as a ground-glass neck flask, distillation adapter (distillation tail), collecting flask, thermometer, water cooler(straight cooler), and distillation head, etc.
all the parts are fixed with clips, nuts, and clamps. these are fixed to a rack. before using, we must check that all fasteners are firmly tight. two clamps are attached in such a way that one to the straight condenser and the other to the mouth of the round bottom flask. besides this, the mount is secured with two clips to the ends of the straight coolant.
- we use a heating plate as a heat source that is present with or without magnetic stirring.
- porous plate or a magnet is used for 1 or 2 pieces for homogeneous boiling.
- the distillation head is responsible for position the thermometer and also diverting the vapor straight direction to the refrigerant.
- all the pieces of apparatus are joined with each other in such a way that their ends have ground glass joints.
- the thermometer is placed at a lower level of the sideline of the distillation connector. in this way, the distillation vapor stream and the measurement are correct.
- the cooling circuit is connected to make a water inlet keeping closest to the distillation bottom.
As the solution heats up and reaches the boiling point of the most volatile component, some molecules pass into the gas phase and rise towards the condenser.
The condenser is a glass tube with separate inner and outer sections. The steam passes through the inner section of the condenser, where it is condensed into a liquid by the cold water that flows in the outer section of the condenser.
This condensed vapor is called distillate and is collected in an Erlenmeyer flask or graduated cylinder.
As the distillation progresses, the temperature necessary to boil the solution increases, due to the fact that the more volatile component that boils before disappears.
Therefore, the composition of the distillate changes over time. At the beginning of the distillation, the distillate is rich in the most volatile component; in the middle of the distillation, the distillate contains a mixture of the two components; and in the end, the distillate obtained is rich in the least volatile component.
Simple distillation methods
There are different methods to carry out the distillation. When this procedure is performed in a laboratory, an apparatus called alembic is usually used. This object is placed in a container, which serves to store the mixture. This mixture will be separated by its different components.
In turn, a condenser is applied to cool the vapors that are generated during the process. It is just in that phase where it returns to a liquid state. Finally, another container is used to store the concentrated liquid
Simple distillation usually works by applying heat to the different liquid components present in the same mixture. The trick is to take advantage of the different boiling points of each of these substances that will be separated. For example, distillation is observed naturally in the process of water, which when it reaches its boiling point – which is 100ºC – results in the condensation of clouds and later rain.
Simple Distillation Examples
Some examples of the use of simple distillation applied to various components are explained below.
First, we have the distillation of water and alcohol. First, you have a solution of alcohol in water that has a concentration of 50%. In this case, the boiling point of the alcohol is known to be 78.4 ° C. Instead, it happens that the boiling point of water is 100 ° C. In this case, it is not possible to obtain pure alcohol
The first step is to heat the mixture to the boiling point of alcohol, as it is the most volatile liquid between the two. The vapor that is formed will have a proportion that is greater than that of alcohol, in turn, there will be a higher concentration of water since there are similarities in the boiling point.
The liquid obtained from this process will result in a higher percentage of alcohol. When the same liquid is subjected to successive distillations, it is possible that a more concentrated solution of alcohol can be obtained, but it is not pure. They are because the steam will continue to have traces of water, this is known by the name of azeotrope
Another example of simple distillation is that used during the separation of a liquid and a solid. In a solution containing salt and water, it results in a liquid that can be volatilized to a compound that is not volatile, upon reaching a very high boiling point. The result is salt, when the solution is distilled pure water is obtained from the condensed liquid. At the bottom of the sea, this method is used and sedimentary salts will be found during the distillation.
When alcohol is separated from glycerin in an ethyl alcohol mixture, we also see an example of distillation. In this case, the boiling point is 78.4ºC for alcohol and that of glycerine is 260ºC. During the simple distillation process, a vapor is formed which will have a much higher percentage than alcohol, being practically close to one hundred percent.
It is used to separate liquids with [boiling point] below 150 ° C from non-volatile impurities, or to separate two-component mixtures that boil with a boiling point difference of at least 60-80 ° C. Mixtures of substances whose boiling points differ from 30-60 ° C can be separated by repeated simple distillations, collecting enriched fractions of one of the components during the first distillation, which are re-distilled.
To ensure homogeneous boiling and no projections, a piece of the porous dish (or magnetic stirring) is introduced into the flask. The liquid to be distilled is put into the flask (which should not be filled much more than half its capacity) and heated with the heating plate.
When the boiling temperature of the liquid is reached, the appreciable production of vapor begins, condensing part of it in the thermometer and on the walls of the flask. Most of the vapor passes into the refrigerant where it condenses due to the cold water current that rises through the jacket of the refrigerant. The distillate (condensed steam) drains into the collecting flask through the extension set.
A layer of solid at the bottom of the distillation flask can cause violent jumps during distillation, especially if strong local heating is used at the bottom of the flask. Heating a flask that has a certain amount of solid deposited at the bottom must always be done by means of a bath.
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