Diffusion

Diffusion is the movement of particles from a region of high concentration to a region of low concentration until they are evenly distributed. Diffusion is important for our sensing of the world around us. It is the way smell reaches us, whether they are pleasant, unpleasant or harmful.

DIFFUSION IN LIQUIDS

Aim: - To see whether diffusion takes place in liquid.

Materials needed: - beaker, spatula, water, potassium permanganate.

Method: - 1. Pour water into beaker.

2. Place a few crystals of potassium permanganate into the beaker of water.

3. Leave it to stand for some time.

Observation: - At first the water around the crystal becomes purple eventually the crystal dissolve completely and the whole solution turns purple.

Explanation: - Both the crystals and water are made up of particles. The color spread because purple particle leave the crystal and mix with water particles.

Conclusion: - Diffusion in liquid takes place.

DIFFUSION IN GASES

Aim: - To see whether diffusion take place in Gases.

Materials needed: - gas jars, glass plate, bromine liquid.

Method: - 1. A few drop of liquid bromine are put into the gas jar.

2. Immediately cover the top with the glass plate.

3. Place another gas jar upside down on the jar of bromine vapor. Then remove the glass plate.

Observation: - The reddish brown color spreads up in both jars.

Explanation: - Both air and bromine are made up of tiny particles. Each collides with each and bounce in all directions so that they become evenly spread.

Conclusion: - Diffusion takes place in gases.

FACTORS AFFECTING THE RATE OF DIFFUSION

There are certain factors that can increase or decrease the rate or speed to diffusion. They are temperature and mass.

TEMPERATURE

Aim: - To see how temperature effects the rate of diffusion.

Materials needed: - • Beaker

• Spatula

• Water

• Copper (II) sulphate ( blue in colour)

Method: - • Poor hot water in one beaker and cold water in another beaker.

• Place a few crystals of copper (II) sulphate into two beakers.

• Observe the time taken for diffusion to occur in two beakers.

Observation: - Blue copper (II) sulphates diffuse faster in hot water than in cold water.

Explanation: - When the temperature increased particles gain more energy and moves faster, therefore diffusion takes place at a faster rate.

Conclusion: - The higher the temperature faster in the rate of diffusion.

MASS

Aim: - To see how mass effects the rate of diffusion.

Materials needed: - • Cotton wool

• Concentrated ammonia

• Concentrated hydrochloric acid

• Glass tube

Method: - • Soak cotton wool in concentrated ammonia and concentrated hydrochloric acid.

• Place the two cotton wool at the ends of the glass tube.

Observation: - After above 10 minutes a white ring of smoke forms closer to the cotton wool soaked in concentrated hydrochloric acid.

Explanation: - Ammonia and hydrogen chloride gas particles diffuse along the tube. When they meet ammonia and hydrogen chloride create together forming a white solid (ammonium chloride). The fact that white ring is formed more towards the hydrochloric acid end shows the hydrogen chloride gas particles being heavier (having more mass) travels much slowly and ammonia being light travels much faster.

Conclusion: - The lighter particles travels more faster and diffuses more faster.

EVERY DAY EFFECTS OF DIFFUSION

Diffusion in gases

EG: - 1. Spread of perfumes in air.

2. Smell of cooking in the house.

3. Smell of flowers in the garden.

Diffusion in liquids

EG: - 1. Spread of coffee grains in water

2. Spread of tea powder in water while preparing tea.