A mixture is formed when two or more substances combine together so there is no chemical reaction between them. Since the constituents of a mixture are not chemically combined, so they can easily be separated from each other by certain physical methods. There are many substances that naturally do not exist in pure form and need to be separated from mixtures they are contained in. Some common methods of separating mixtures that are in practice for years include evaporation, filtration, simple distillation, fractional distillation and chromatography. Let us try and conduct a few experiments to see how different mixtures can be separated. This will be a good idea for a Science project and at the same time, good information for many observers. However, you will require a few things in order to carry out this experiment.
- Salt (1 table spoon)
- Filter paper
- Sand (1 table spoon)
- One beakers
- China Dish
- Bunsen burner
Water & Sand
Warm some water in a pan and pour about half of it in a regular cup. Now with the help of a tea spoon, add a spoonful of sand into the warm water and note what you observe.
Salt & Water
Take another cup of the same size (as the previous one) and fill it with the remaining warm. Same as in the previous step, add a table spoon of salt into warm water and again note the observations.
Filtration of Sand & Water
Put a funnel into a beaker and fix paper over the funnel. Pour in all the sand and water mixture slowly. You will see that water distills inside the beaker and the sand is left at the surface of the filter paper.
Filtration of Salt & Water
Now try the same with salt water. If you taste salt water before and after filtering it, you will have the same taste suggesting that it cannot be separated by filtration.
Evaporation to dryness
Pour the salt solution in a china dish and place it on a Bunsen burner. Allow the water to evaporate and observe what happens. It will be noticed that the water evaporates and salt is left behind.