Wednesday, 13 February 2013

1.7 describe experimental techniques for the separation of mixtures, including simple distillation, fracti onal distillation, filtration, crystallisation and paper chromatography





Filtration
This consists of a barrier which one component f a mixture can pass through but the other is caught by.
e.g water goes through filter paper, rocks are caught by it.

Distillation
One substance is evaporated off.
e.g salt water is heated to 100 degrees; water evaporates off (it rises and the goes down into the condenser where it is cooled back into water), the salt is left in the original flask. See diagram.

Fractional distillation
The mixture is evaporated and rises up the tube.
Different substances have different boiling points and so will condense at different temperatures; as the mixture travels up the tube the temperature decreases, substances begin to condense at different places (due to the change in temperature) and are collected. This separates the mixture into its different parts.

Crystallisation
A solution is warmed allowing the solvent to evaporate, the solution is now left to cool and will form crystals.

Chromatography
chromatography paper is placed in a substance, the different components of the substance will travel at different speeds (due to the size of their particles.)

5 comments:

  1. simple distillation: separates liquid from a dissolved solid

    ReplyDelete
  2. Hi, do u need to be able to draw diagrams of these experiments

    ReplyDelete
    Replies
    1. This comment has been removed by the author.

      Delete
    2. Sometimes you need to draw in IGCSE Triple Science, but it's best to always be prepared. And don't forget to use a ruler and a pencil!

      Delete
  3. The Chemistry Syllabus has changed…

    Here is a New blog for the 2017 Syllabus:

    https://igcse-chemistry-2017.blogspot.hk/

    ReplyDelete