Particle Theory of Matter - Convection

Aim -  To observe convection in a liquid
Equipment: 200 mL beaker, water, tweezers, a crystal potassium permanganate, a drinking straw, Bunsen burner, heat mat, tripod and gauze mat.

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 200 mL beaker with 150 mL of cold water.
3. Place the beaker on top of the tripod and gauze and allow it to settle for a few minutes.
4. Carefully insert a drinking straw down one side of the beaker, ensure 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 on the bottom of the beaker.
6. Very gently, so to not disturb the water, remove the straw.
7. Light the Bunsen and slide it under the tripod so that you are only heating the outside of the beaker where the crystal is. Observe. 

 Observation:
The crystal dissolved and made a thick purple cloud and dissolved more rapidly on the side of the beaker. The purple moved up the beaker side and then formed a big circle and made its way up around the beaker.

Explanation:  This is because of the convection current