Is Matter Around Us Pure

1. Crystallization or Evaporation
2. Sublimation
3. Centrifugation or Sedimentation
4. Chromatography
5. Centrifugation
6. Separating funnel
7. Hand-picking
8. Magnetic separation
9. Winnowing
10. Centrifugation.

Take the solvent, water, in a kettle. Heat it. When the solvent boils, add the solute, milk. Milk and water forms a solution. Then pour some tea leaves over a sieve. Pour slowly hot solution of milk over tea leaves. Colour of tea leaves goes into solutionas filtrate. The remaining tea leaves being insoluble remains as residue. Add requisite sugar which dissolves and the tea is ready.

1. Saturated Solution - a solution in which no more of the solid (solute) can be dissolved at a given temperature is called a saturated solution. Suppose 50 gm of a solute is the maximum amount that can be dissolved in 100 gm water at 298 K. Then 150 gm of solution so obtained is the saturated solution at 298 K.
2. Pure Substance - A pure substance consists of a single of matter or particles and can not be separated into other kind of matter by any physical process. Pure substances always have the same colour, taste and texture at a given temperature and pressure. For example, pure water is always colourless, odorless and tasteless and boils at 373 K at normal atmospheric pressure.
3. Colloid - Colloids are heterogeneous mixtures the particle size is too small to be seen with a naked eye, but it is big enough to scatter light. The particles are called the dispersed phase and the medium in which they are distributed is called the dispersion medium. Colloids are useful in industry and daily life. A colloid has the following characteristics:
   (1) It is a heterogeneous mixture.
   (2) The size of particles of a colloid lies between 1 - 100 nm and can not be seen by naked eyes.
   (3) The particles of colloid can scatter a beam of light passing through it and make the path visible.
   (4) The particles of colloid can not be separated from the mixture by filtration. The process of separation of colloidal particles is known as ‘centrifugation’.
   (5) They do not settle down when left undisturbed. In other words colloids are quite stable e.g. smoke, milk, fog, cloud etc.
   
4. Suspension - A ‘suspension’ is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. A suspension has the following characteristics:
   (1) It is a heterogeneous mixture.
   (2) The size of particles of a suspension is greater than 100 nm and is visible to naked eyes.
   (3) The particles of suspension can scatter a beam of light passing through it.
   (4) The particles of a suspension settle down when left undisturbed.
   (5) The particles of a suspension can be separated from its mixture by filtration.

Homogeneous mixture - soda water, air, vinegar, filtered tea.
Heterogeneous mixture - wood, soil.

Every liquid has a characteristic boiling point at 1 atmospheric pressure. If the given colourless liquid boils exactly at 373 K at 1 atmospheric pressure, then it is pure water. If the boiling point is different then the water is contaminated.

(a), (c), (d), (e) and (f) are pure substances.

(b) and (d) are colloids and will show Tyndall Effect.

Elements - sodium, silver, tin, silicon.
Compounds - calcium carbonate, methane, carbon dioxide.
Mixtures - soil, sugar solution, coal, air, soap, blood.