Particle Theory of Matter- Convection

When particles are heated the distance between the particles increase. This means that objects will expand. When liquids or gases expand they become less dense. A gas or liquid which is less dense will rise through a more dense or liquid. This is the explanation for the well-known tendency of hot fluids to rise and col fluids to sink. Scientists call this process convection.

Observing Convection l

Aim: To observe convection in a liquid.

Equipment: 200 mL beaker, tweezers, a crystal of potassium permanganate, a drinking straw, bunsen burner, heat tripod and gauze. 

Method:

1. Set up a bunsen burner on a heatproof mat. put the gauze mat on the tripod but leave it just to one side of the bunsen burner.
2. fill a 200ml beaker with 150 ml of cold water.
3. place the beaker on top of the tripod and gauze and allow in to settle for a few minutes.
4. Carefully insert a drinking straw down one side of the beaker, ensuring the straw is touching the bottom of the beaker. be careful as you do not want to disturb the water too much.
5. using tweezers drop a crystal of potassium permanganate down the inside of the straw. wait for the crystal to settle on the bottom of the beaker.
6. very gently so to not disturb the water remove the straw. 
7. light the Bunsen burner and slide it under the tripod so that you are only heating the outside of the beaker where the crystal is. Observe.

Observation: 

As the water got hotter the potassium permanganate crystals started to become more vibrant.