C2.1.7 - Purification And Checking Purity Flashcards Preview

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Flashcards in C2.1.7 - Purification And Checking Purity Deck (8)
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What can you use to tell if a substance is pure?

Thin-layer chromatography or paper chromatography


Which is better at checking pure substances - paper or thin-layer chromatography?

Thin-layer chromatography


What are the advantages of using thin-layer chromatography over paper chromatography for checking pure substances?

It is quicker
It is more sensitive, so a smaller substance can be used
There is a larger range of chemical phases to choose from
You can also scrape an individual spot for further analysis from a thin-layer chromatogram by using gas chromatography


What do you need to know about the substances in order to use the correct separation method?

The properties of the substances


How do you separate insoluble substances?

Dissolving followed by filtration


How do you separate solutions?

Crystallisation to obtain the solute
Simple distillation to obtain the solvent


How do you separate two or more substances in the liquid state?

Fractional distillation


How do you separate coloured soluble solutions?

You use paper chromatography or thin-layer chromatography