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Secondary I ‱ 2yr.


I have to separate mixtures in my laboratory, but I no longer recall techniques. Could you please remind me?

Thanks a lot!


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Explanations (1)

  • Explanation from Alloprof

    Explanation from Alloprof

    This Explanation was submitted by a member of the Alloprof team.

    Team Alloprof ‱ 2yr.

    Thank you for your question😉

    There are seven techniques for separating mixtures.

    • Evaporative Separation

    This technique allows you to separate the constituents of a mixture by their different boiling points. This technique works whether the mixture is homogeneous or heterogeneous and whether its phases are liquid-liquid or liquid-solid. To do evaporation, you need to heat your mixture until it boils, using a hot plate. Thus, one of the constituents will evaporate, and the other will remain in the beaker. A weak point of this technique is that it is impossible to recover all the mixture constituents.

    Warning!! Do not continue heating when one of the liquids has evaporated as the second may evaporate as well if heating continues.

    • Separation by settling

    This technique is used for heterogeneous mixtures which have at least one liquid phase. This method is very simple. Once the mixture is in a beaker, you have to wait for a clear line to form between the two substances in the mixture. Once the substances are separated, and the line has appeared, the supernatant liquid should be poured slowly into a second beaker.

    • Decantation with a separating funnel

    This technique is carried out only with heterogeneous liquid mixtures. The principle is similar to decantation, except that the separation takes place in a separating funnel. First, the following setup is necessary :

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    Then, add the liquid and wait for it to settle, as in the image above. Once a line between the two substances appears, separation can begin. Open the valve on the ampoule and collect the liquid in a beaker below. You have to be careful to make sure all the liquid from the first substance is poured into the beaker and the second substance stays in the ampoule.

    • Separation by filtration

    This technique is usually done with heterogeneous liquid-solid mixtures. The first step is to perform the following assembly:


    Once the filter paper is wet, you need to pour your mixture into the funnel. The liquid will pass through the filter paper, will end up in the beaker, and the solid will remain in the filter paper.

    • Separation by Distillation

    This technique is practically identical to separation by evaporation except that it allows all the constituents to be collected. This technique requires a refrigerant tube. The tube will store the gas component, which evaporates and cools it to make it liquid again. It will then end up in another beaker when the separation is complete.

    • Separation by sieving

    This technique only allows the separation of heterogeneous solid-solid mixtures. To do this technique, you have to use the sieve. This tool consists of a series of levels and at each level is a tray with smaller and smaller holes. Therefore, when the mixture is poured into the sieve, each constituent is separated and grouped according to its size. The image below shows an example of different levels.

    • Separation by centrifugation

    This technique is very similar to decantation. It speeds up the decantation process using the centrifuge force. The mixture should be put in test tubes and placed in the centrifuge. Once they have spent a few minutes in the centrifuge, they can be removed, and it is sufficient to separate the supernatant liquid into another beaker.

    Don't hesitate to let us know if you have any other questions😊

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