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SS1: CHEMISTRY - 2ND TERM

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  1. Kinetic Theory of Matter | Week 1
    3 Topics
    |
    2 Quizzes
  2. Kinetic Theory of Matter & Gas Laws 1 | Week 2
    3 Topics
    |
    2 Quizzes
  3. Gas Laws II | Week 3
    3 Topics
    |
    2 Quizzes
  4. Gas Laws III | Week 4
    3 Topics
    |
    2 Quizzes
  5. Gas Laws IV | Week 5
    3 Topics
    |
    2 Quizzes
  6. Mole Concept | Week 6
    5 Topics
    |
    2 Quizzes
  7. Acid, Bases and Salts I | Week 7
    7 Topics
    |
    2 Quizzes
  8. Acid, Bases and Salts II | Week 8
    6 Topics
    |
    2 Quizzes
  9. Acid, Bases and Salts III | Week 9
    3 Topics
    |
    2 Quizzes
  10. Acid, Bases and Salts IV | Week 10
    4 Topics
    |
    1 Quiz
  11. Acid, Bases and Salts V | Week 11
    5 Topics
    |
    1 Quiz



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We learnt that matter is made up of tiny particles. The fact that these particles are in constant motion is being exhibited in the following natural phenomena that supports kinetic theory

1. Brownian movement: Brownian movement or motion is the zig-zig, irregular motion exhibited by minute particles of matter when suspended in a fluid.

It was first observed by a British botanist Robert Brown in 1827 when studying pollen grains. He observed that when pollen grains is suspended into water under a microscope, the pollen grains move about in a zig-zag manner. The movement is known as Brownian movement.

2. Diffusion: This is the movement of molecules of a substance from a region of higher concentration to that of lower concentration. For instance, if a perfume is sprayed in one corner of a room, its molecules (vapour) will move or diffuse to all parts of the room within a short time.

Diffusion is fastest in gases because gas molecules have more kinetic energy than liquid and solid particles.

3. Osmosis: Osmosis is the movement of water molecules or other solvents from a region of lower concentration to a region of higher concentration through a semi-permeable membrane. For example, the intake of water in the soil by plants through the roots is by osmosis.

4. Dialysis: Dialysis is the process whereby crystalloids in a true solution pass through a permeable membrane. For example, a solution of starch and sodium chloride in water can be separated by placing the mixture in a vessel on one side of a semi-permeable membrane and water on the other side. Sodium and chloride ions will diffuse across the membrane. But the larger particles (starch/colloidal solution) will not diffuse.

This method was originated by Thomas Graham. The substances that diffuse through the membrane are crystalloid, while the ones that remain within the membrane are the colloids.

5. Tyndal Effect: Tyndal Effect is the scattering of light as a light beam passes through a colloid. The individual suspension particles scatter and reflect light, making the beam visible.

6. Evaporation: Change of state from liquid to vapour. The rate of evaporation increases with an increase in temperature.

7. Sublimation: Change of state from solid to gas and from gas to solid. vice versa. When a solid is heated, the molecules overcome the cohesive forces and become rapidly changed to gas.

Theory Questions

1. State the Kinetic theory of Matter and outline three natural phenomena that support it. 

2. (a) Give three differences between Solid and Liquid

   (b) Which state of Matter contains particles that are:

    (i) Readily compressed (ii) Held firmly by some forces of Cohesion (iii) Involved in rapid motion

3. (a) Explain how impurity in a substance affects

      (i) Melting point (ii) Boiling point

(b) State one Similarity and two differences between Boiling and Evaporation

4. Write short notes on the following

      (a) Latent heat of Vaporisation 

      (b) Tyndal Effect

      (c) Dialysis 

      (d) Brownian Motion

5. (a) Evaporation causes Cooling. Explain

    (b)

Screen Shot 2021 01 19 at 5.24.00 PM

The above is a diagrammatic representation of the changes in the states of Matter (i) Name all the processes involved from 1 to 6 (ii) What can bring about one of these changes?

     (c) Explain why an increase in the temperature of a gas of fixed volume results in an increase in its pressure.

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