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Solutions, Solvents, Mixtures?

By Joshua Tompsett

Mixtures:

This is where one or more substances are combined together, although they aren't chemically bound and therefore can be relatively easily separated, a good tool for there separation is filter paper. A good examples of these are, air is a mixture of many different gasses.



Solutions:

When you dissolve a solid into a liquid you make a solution. An example of this that you have have done is if you have some water and into it you put some salt, the salt will start to dissolve and the particles become equally dispersed throughout the liquid, this process can be hastened by stirring the water or adding heat. In this the salt would be the solute - the thing being dissolved, and the water would be the solvent - the thing in which the solute is dissolved in. This can't be undone via filter paper.


Purity:

What is a pure substance? Well, a pure substance is a substance that only contains itself. For example in water it can have lots of other added chemicals but that makes it impure. Well, is it important? Well if your medicine isn't pure it might have a harmful impurity. Don't worry there are ways to test for impurities. For example if you boil ethanol and it boil at 78, then its pure. But if you boil ethanol and it boils at 83, then it is fairly impure.

Separations:

Filtering:

If you have an insoluble substance and a liquid, you can put the mixture on filter paper, which is in a cone with a receptacle to catch the liquid, and it will catch the filtered liquid.

Crystallisation:

It is where you evaporate a liquid to get the dissolved solution, this can be extended to separate to solids if one is soluble. This is done by placing the mixture into a liquid where only one of the solids can dissolve and then the one that can dissolve will dissolve and then you can filter the substance to remove the insoluble substance and then if you want, to have the dissolved substance you just have to evaporate the liquid.

Simple Distillation:

You can create a pure liquid via boiling the liquid and removing the impurities and then have the liquid condense so that it becomes a pure or distilled version of the liquid.

Fractional Distillation:

This is used when you have two different liquids with two different boiling points and you wish to separate them. This is done by boiling the two liquids at the boiling point of the lower one say methanol and ethanol. The methanol boils and becomes gas and goes up and when it gets there it cools and condenses on these small orbs and heats up the orbs and then it will go back down and boil again. The need for these orbs is while the ethanol isn't boiling it will still evaporate and this is to prevent it from mixing with the methanol and actually separating them fully. This process continues until the orbs are also at the same temperature as methanol's boiling point. Then the methanol will cool and condense at the top of the beaker and pass through a outgoing tube at the top into another flask. This is continued until you have fully separated the two liquids.

Chromatography:

This is a much more complicated method because it has a simple use where you can break down colours of ink, into there basic colours. This can be done by putting say a drop of green ink onto a piece of chromatography paper and then you proceeded to drop water on it, one drop at a time, and it will be broken down into its basic colours.

Although, it can also be used to identify solutions. This can be done if you say think Y contains A, C and D but not B. First you have to get your substances and place a labelled dot of these solutions. Then you put this into a glass tank which has a small layer of propanone. Then once the propanone has reached the top, you remove the paper and you should see that the dots have moved up and if substance Y did contain A, C and D there should be above Y the same colours inline with the dot of the same colour. This will show which it contains.



Sources:


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