2.1.1 Laboratory Activity : Investigating the diffusion of particles in a gas, liquid and solid

Laboratory Activity 2.1.1: Investigating the diffusion of particles in a gas, liquid and solid

Aim: Investigating the diffusion of particles in a gas, liquid and solid
Hypothesis : Diffusion takes place in a gas, liquid and solid. The rates of diffusion in a gas, liquid and solid are in decreasing order.
Problem statement: Investigating the diffusion of particles in a gas, liquid and solid
Variable:

	»	Fixed variable: Temperature
	»	Manipulated variable: Medium of diffusion
	»	Responding variable: Rate of diffusion

Material: » Liquid bromine » Potassium permanganate crystals » Water » Hot jelly solution

Apparatus: » Two gas jars with plastic covers » Petri dish » Teat pipette » Spatula » Rubber stopper » Boiling tube

Procedures:

	►	(A) Diffusion in a gas 1. The animation below shows the arrangement and the results of the experiment. 2. A few drops of liquid bromine are dropped into a gas jar using a teat pipette. 3. The gas jar is covered with a gas jar cover. 4. Another gas jar is placed upside down on top of the first jar. 5. The cover is removed and any colour change is recorded. 6. The time taken for the brown bromine vapour to spread into the second gas jar is recorded.
	►	(B) Diffusion in a liquid 1. The animation below shows the arrangement and the results of the experiment. 2. A petri dish is filled with water. 3. A few potassium permanganate crystals are placed at the bottom of the water using a spatula. 4. Any colour change is recorded. 5. The time taken for the purple permanganate ions to spread throughout the water is recorded.
	►	(C) Diffusion in a solid 1. The animation below shows the arrangement and the results of the experiment. 2. Some freshly cooked jelly solution is placed into a boiling tube until it is almost full. 3. The jelly is allowed to set. 4. A small potassium permanganate crystal is placed on top of the jelly. 5. The boiling tube is then stoppered using a rubber stopper. 6. Any colour change is recorded. 7. The time taken for the purple permanganate ions to spread throughout the solid jelly is recorded.

Discussion:

	►	Diffusion has taken place in the gas (air in experiment A), liquid (water in experiment B) and solid (jelly in experiment C).
	►	The rates of diffusion of the particles in the solid, liquid and gaseous states differ. It is highest in gases, lower in liquids and the lowest in solids.
	►	This shows that there are more and bigger spaces between particles in the gas. The spaces between liquid particles are smaller. The particles in the solid state are very close with little space between them.
	►	The occurrence of diffusion proves that matter (bromine and potassium permanganate) consist of particles in constant motion
	►	The diffusion experiments show that particle posses the kinetic energy and are in constant motion.

Conclusion:

	►	Bromine is made of tiny and discrete particles.
	►	Potassium permanganate is made up of tiny and discrete particles (ions).

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