Movement of Particles / Experiments

Question 1

What is Diffusion?

Answer 1

Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.

Net Movement - The movement of all of the particles considered together as a group.

Question 2

What is the Potassium Manganate(VII) and Water experiment?

Answer 2

1. If you take a beaker of water and place some potassium manganate(VII) at the bottom, the purple colour slowly spreads out to fill the beaker.
2. The particles of the potassium manganate(VII) will diffuse out among the particles of water.
3. It’s the random motion of particles in a liquid that causes the purple colour to eventually be evenly spread out throughout the water.

Potassium Manganate(VII) solution can also be diluted by adding water. This is because the potassium manganate(VII) particles would spread further out.

Question 3

What is the Ammonia and Hydrogen Chloride experiment?

Answer 3

1. Aqueous ammonia (NH3) gives off ammonia gas.
   Hydrochloric acid (HCl) gives off hydrogen chloride gas.
2. The NH3 gas diffuses from one end of the tube and the HCl gas diffuses from the other. When they meet they react to form ammonium chloride.
3. The ring doesn’t form exactly in the middle of the glass tube - it forms nearest the end of the tube where the hydrochloric acid was.
4. This is because the particles of ammonia are smaller and lighter than the particles of hydrogen chloride, so they diffuse through the air more quickly.

Question 4

What is the Bromine Gas and Air experiment?

Answer 4

1. Bromine gas is a brown, strongly smelling gas. You can use it to demonstrate diffusion in gases.
2. Fill half a gas jar full of bromine gas, and the other half full of air - separate the gases with a glass plate.
3. When you remove the glass plate, you’ll see the brown bromine gas slowly diffusing through the air.
4. The random motion of the particles means that the bromine will eventually diffuse right through the air.