C2: Experimental Techniques

Note by Moon&Stars4U, updated more than 1 year ago
Created by Moon&Stars4U about 7 years ago


IGCSE Coordinated Science Chemistry Note on C2: Experimental Techniques, created by Moon&Stars4U on 03/31/2014.

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How does it work?It's a way of separating solutions or liquids which are mixed togetherA bit on ink is placed on the X spot Then the paper is put into waterAs the water rises up the paper, the different dyes travel different distancesThey are separated on the chromatogramThis is used to identify what an unknown liquid is made of 

What is filtration?How does it work?Add a solvent that the solid that is wanted is soluble in, and dissolve it,Filter the mixture to remove the insoluble impurityHeat the solution to remove some solvent and leave to crystalline Filter off the crystals, wash with a small amount of cold solvent and dry them - leaving the pure solid

Identify Simple Chromatograms

How is it used?The solution is warmed in an open containerAllowing the solvent to evaporate, leaving a saturated solutionAs the saturated solution coolsThe solid will come out of the solutionCrystals will start to growThen they are picked up and allowed to cool

The process:The mixture is boiledThe liquid with the lowest boiling point turns to a vapor firstIt then comes off and it is condensed back into a liquid at the top of the fractional columnThe next lowest boiling point liquid comes off, this process continues until all the liquids have been separated One can identify the fraction you want to save by the temperature reading on the thermometer 

The solution is heatedThe liquid boilsTurns into vapor It is then condensed back to the pure liquidThen it's collected 

The purity of solids and liquids:The easiest way of checking the purity of solids and liquids is using heat to find the temperatures at which they melt or boilAn impure solid: Lower melting pointLiquid containing a dissolved solid: higher boiling point than pure liquid solvent 

It's important that manufactured foods and drugs only contain the substances the manufacturers want in themMUST BE PUREDOESN'T CONTAIN ANY CONTAMINANTS

Which method to use:Fractional Distillation is used for liquids that mixA separating funnel is used for liquids that don't mixCrystallization is used for solids that dissolve in liquidsFiltration is used for solids that don't dissolve in liquidsChromatography is used for components of a mixture

Paper Chromatography



Fractional Distillation


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