Content analysis

             

                    CONTENT ANALYSIS

   Standard : VIII

   Subject    : Chemistry

   Unit           : Solutions

   Topic        : Classification of  mixtures

1. SYMBOL

• G

• mL

2. TERMS

• Solution 

• Mixture

• Homogeneous mixture

• Heterogeneous mixture

• True solution

• Colloid

• Suspension

• Solute

• Gravity

• Fog

• Air

• Particle

• Beam

• Dust

3. FACTS

• All solutions are mixtures.

• Mixtures exhibit different nature.

• If the composition of the constituents is the same throughout the mixture, it is known as a homogeneous mixture.

• All solutions are homogeneous mixtures.

• Homogeneous mixtures cannot be seen separately with the naked eye.

• If the components in a mixture are not distributed uniformly, it is known as heterogeneous mixtures.

• Heterogeneous mixtures can be seen separately with the naked eye.

• Particles of solutions cannot be separated by filtration.

• The size of particles in solution, colloid and suspension are not same.

• The size of solute particles present in a solution is so small that it cannot be seen with the naked eye.

• Particles of solution cannot scatter a beam of light. Hence path of light beam is not visible.

• In the case of colloids, the solute (colloidal) particle size is comparatively bigger. Hence, they scatter a beam of light, thus making the path of the beam visible.

• Particles of suspensions are big enough to be seen with the naked eye. The light falling on them is reflected almost completely. They gradually settle down under the influence of gravity.

4. CONCEPTS

• Solution

• Mixture

• Homogeneous mixture

• Heterogeneous mixture

• Colloid

• Suspension

• Solute

• Gravity

5. DEFINITIONS

• SOLUTION

Homogeneous mixture of two or more components in which the particle size is smaller than 1 nm.

• MIXTURE

Mixture is two or more substances that are mixed together but not chemically combined and that may vary in proportion.

• HOMOGENEOUS MIXTURE

It is a gaseous, liquid or solid mixture that has the same proportions of its components throughout a given sample.

• HETEROGENEOUS MIXTURE

It is a mixture that is non-uniform and contains smaller component parts. 

• COLLOID

Mixtures in which microscopically dispersed insoluble particles of one substance are suspended in another substance.

• SUSPENSION

A heterogeneous mixture in which the solid particles are spread throughout the liquid without dissolving it.

• SOLUTE

A substance that is dissolved in a solution is called a solute.

• GRAVITY

A force that attracts a body towards the center of the earth or any other physical body having mass.

6. PROCESS

• Take equal amount of water in three separate beakers. Add copper sulphate crystals in the first, milk in the second and chalk powder in the third beaker. Stir them well. Keep the beakers undisturbed for some time.

• Prepare a solution by adding 2g sodium thiosulphate (hypo) in a beaker containing 50 mL of water. Arrange the beaker in the path of a beam of light and add a few drops of dilute hydrochloric acid. Stir the solution. Observe for a while. Record your observations.