Methods of purification by Visva

Page 1

Filtration

Filtration is used to separate solid in liquid which are undissolved. This is achieved by pouring the solution through filter paper (also known as filtrate) in a filter funnel. which results with solid staying on surface this is call the residue.

The solids should be washed with distilled water to remove any solution between the particle. the solid then dried in an oven.

Page 2

Decanting

Decanting is simply off pouring the solution. It is suitable for solids that have very heavy particles- for example, to separate sand and water

Centrifuge

A centrifuge is a machine which spins test tube around and around at high speed. This pull the solid to the bottom of the tube, You decant the liquid after that.

Page 3

Crystallisation

Crystalline is used to obtain a crystalline solid from a solution.

Method

The solution is gently heated in an evaporating basin to concentration it.

The solvent, usually water, is evaporated until the crytsallisation point is reach.

The concentrated solution is then left to cool crystals eventually form at the bottom of the evaporating basin.

These can then be filtered off and dried

If two dissolved substances have different solubilites at different temperature , fractional distillation can be used.

Method

A warmed concentrated solution is cooled

The solute with lower solubility forms

higher solubilty remains and can be filter out

Page 4

Solvent extraction

Solvent extraction is used to separates two dissolve solute in a solutions.

This useful if solute is volatile.

This process is achieved using a second solvent but can't mix the solution (immiscible)

They are put into filter funnel and shaken.

(effect can be seen in pictuer below)

Page 5

Simple Distillation

Simple distillation is used to separate solvent from the solution

The solution is heated.

the steam escapes

solute is left behind as a solid

The steam go through a condesenr

Condeser is cold and turn vapour back