C2: Experimental Techniques

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How does it work?

It's a way of separating solutions or liquids which are mixed together

A bit on ink is placed on the X spot

Then the paper is put into water

As the water rises up the paper, the different dyes travel different distances

They are separated on the chromatogram

This 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 impurity

Heat 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 container

Allowing the solvent to evaporate, leaving a saturated solution

As the saturated solution cools

The solid will come out of the solution

Crystals will start to grow

Then they are picked up and allowed to cool

The process:

The mixture is boiled

The liquid with the lowest boiling point turns to a vapor first

It then comes off and it is condensed back into a liquid at the top of the fractional column

The 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 heated

The liquid boils

Turns into vapor

It is then condensed back to the pure liquid

Then 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 boil

An impure solid: Lower melting point

Liquid 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 them

MUST BE PURE

DOESN'T CONTAIN ANY CONTAMINANTS

Which method to use:

Fractional Distillation is used for liquids that mix

A separating funnel is used for liquids that don't mix

Crystallization is used for solids that dissolve in liquids

Filtration is used for solids that don't dissolve in liquids

Chromatography is used for components of a mixture

Paper Chromatography

Filtration

Crystallisation

Fractional Distillation

Distillation