ib chem oxford topic 1 mrs moore

What’s an element?

A pure substance unable to be broken down into a simpler substance by chemical means

What’s a compound?

A pure substance formed from 2 or more dofferent elements chemically joined

What’s a mixture?

Something which contains more than 1 element or compound that are not chemically bonded

What’s a homogeneous mixture?

A mixture with the same uniform appearance and composition throughout

What’s a heterogeneous mixture?

A mixture containing visibly different substances or phases e.g sand and water

What’s a separation technique used to separate a heterogeneous mixture?

Filtration

What kind of filtration do you use if the solid particles in a heterogeneous mixture are very small

Vacuum filtration

When is evaporation Anf filtration used?

If only 1 component of a mixture is soluble in a solvent

Steps of evaporation and recrystallisation

1. mixture warmed with solvent to dissolve the soluble part

2. Solution filtered

3. Solvent evaporated

4. Filter w Büchner funnel

5. Let crystals dry then wash with distilled water

What’s a separatory funnel used for?

To separate 2 immiscible liquids

Steps for separatory funnel

Shake mixture with stopper on

Allow to stand

Once 2 layers have formed remove stopper

More dense layer will run off when the tap is open