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Particulate Nature of Matter - Physics Form 1 Coursework e-Content CDs

Diffusion in Liquids (potassium manganate (VII) solution in water)

In the following demonstration, a drop of potassium manganate (VII) solution is added to water. Observe what happens after the drop is added.

Diffusion takes place largely in fluids (liquids and gases).


Take a beaker half filled with water with a funnel in it.  Using the mouse drag the copper (II) sulphate solution and pour it through the funnel.  Allow the set up standing undisturbed for some time.  What do you observe?

Diffusion takes place largely in fluids (liquids and gases)



Entry Competence






By the end of this lesson you should be able to:

  1. Show that matter is made up of tiny particles
  2. Describe experiments to show that particles of matter are in continuous, random motion
  3. Explain the states of matter in terms of particles

Experiments on Matter

To investigate properties of matter, we need to carry out experiments. Our experiments will involve cutting a piece of paper, breaking a solid, dissolving a solid and allowing water to pour (leak) from a hole at the bottom of a container. Observe what happens in each experiment and use your observations to make conclusions about the properties of the material or substance used in each case.

Cutting a piece of paper

In the activity represented below, a piece of paper is cut severally.

What happens to the piece of paper?

What can you say about the nature of paper?


A piece of paper can be split into even smaller pieces; so it consists of partcles.

Breaking a Stone

Observe the effect of hitting a stone with a hammer. From your observation, suggest what a solid consists of.


The solid consists of particles.

Dissolving a Solid

Click on the button and observe what happens when solid potassium manganate (VII) is added to water. What does the observation suggest about the nature of potassium manganate (VII)?


Potassium manganate (VII) consists of particles.

Pouring a Liquid

In the set-up below, the upper container holds water but has a small hole at the bottom. Click on the play button and take observations. From the observation, what conclusion can you make regarding the nature of water?


The large mass of water in the container can divide into smaller units (drops). So water consists of small particles. All these demonstrations involving breaking a solid, dissolving a solid and pouring a liquid, together show that matter consists of small particles. This is the basis of particulate theory which states that matter consists of invisible particles.

Tapping Smoke


  • Drag a lit match stick into the tin can to ignite the paper.  This should generate the smoke
  • After some time drag the tin cover onto the tin can

  • Record the observation in the text box.

  • Observation

    The smoke comes out


    Matter, whether solid, liquid or gas is made up of tiny, invisible particles

    Brownian Motion

    Observe the behaviour of matter as shown in the animation below.

    The movement you have just observed may be simulated as shown.

    What have you observed about the movement of particles?


    Particles of matter move continuously and in all directions (randomly).

    States of Matter

    Characteristics of solids

    • Solids have definite shape.
    • Particles are more closely packed.
    • Each particle vibrates, so there is no overall change in position.

    Characteristics of liquids

    • Liquids take the shape of container.
    • Motion of particles is random, with a little rotation and little vibration.
    • Particles are less packed than in a solid.

    Characteristics of gases

    • Gases have no definite shape or volume.
    • Particles are farther apart than in liquids or solids.
    • Motion of particles is random, with a bit of rotation.


    Kinetic Theory of Matter

    To explain the differences in states of matter; that is, how a solid, liquid and gas are different, we need a theory (an accepted scientific explanation of an occurrence). The explanation that particles of matter are in continuous motion is called the kinetic theory.

    Kinetic theory is based on three aspects; that is:

    1. Matter is made up of particles.
    2. The particles are in continuous and random motion.
    3. Particles collide with each other and with any surface without losing their kinetic energy.

    Solids, Liquids and Gases

    Movement of particles

    The animation below shows the movement of particles in the various states of matter, namely: solid, liquid and gas.


    Exansion of Gases

    The set-up below demonstrates the effect of heating a gas. Observe what happens.

    When air (or a gas) is heated, the liquid index moves up steadily. This indicates that, like solids and liquids, gases expand on heating. In fact, gases expand much faster than solids and liquids as indicated by the rapid rise of the liquid index.


    Click on the play button and observe the behaviour of gas particles. What can you say about the general direction of movement of particles?

    If the cover of a cooking pot is opened, the smell of the food soon spreads to other places. The process by which particles spread is called diffusion. Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration.


    If a person wearing a very strong perfume gets into a room, the perfume spreads into the whole room. 

    The situations just described illustrate a process called diffusion. Diffusion is the movement of particles of fluid from a region of high concentration to one of low concentration.

    Activity 3: Diffusion in Gases

    In the following demonstration, one piece of cotton wool is soaked in hydrochloric acid and another in ammonia solution. They are then plugged into the two ends of a glass tube simultaneously. The photograph on the next page shows how the glass tube is clamped while the accompanying animation shows the movement of particles.


    One of the bottles contains concentrated hydrochloric acid and the other, ammonia solution. 


    The two vapours diffuse from both sides and meet at point P to form a white ring. Ammonia particles are less dense and lighter than hydrogen chloride particles.  Therefore ammonia particles diffuse faster and travel farther along the tube than hydrogen chloride gas.


    Since we did not see the whole mass of acid or ammonium chloride flowing, it is their particles that moved to form the ring of ammonium chloride at point P.  Diffusion is a further proof that matter is made up of tiny particles.

    Look for the following words in the puzzle.  Pick the pen using the mouse dip it in any color and circle the correct letters to the word.  Using the color of your choice
    1. ammonia
    2. diffusion
    3. gases
    4. acid
    5. matter
    6. molecules
    7. liquids
    8. atoms
    9. smoke cell
    10. random
    11. solid
    12. rotation
    13. Brownian
    14. kinetic
    15. compress

    Color boxes red, blue, and green, yellow

    Revision Exercises


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