Convection

Aim:
To observe convection in a liquid.

Equipment:
200 mL beker, water, teezers, a crystal of 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 levae it just to one side of the bunsen bruner.
2. Fill a 200 mL beaker with 150 mL cold water.
3. Place a beaker on top of the tripod and gauze mat.
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 permanfanate 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 and slide it under the tripod so that you are only heating the outside of the beaker where the crystal is. Observe.

Results:
The potassium permangante's particles turned the water purple, and as we heated the beaker, the purple particles rose up the beaker.

Discussion:
Convection takes place when heat is transferred through a liquid or a gas by a hotter material moving into a cooler area. The potassium permanganate was slowly set into the beaker of cold water, and the crystal was heated up. As the purple spread, the water heated up, and because hot water is less dense than cold water, the hot water rised up the beaker, bringing the purple with it.