Making a dilution series

Aim:To make dilution series to investigate concentration.

Equipment:

• A potassium permanganate crystal
• Six large test tubes
• Tweezers
• A plastic transfer pipette
• A test tube rack
• 10 ml measuring cylinder

Method:

1. Place the six tubes in a test tube rack.Label the rack with numbers from 1-6.
2. Using the measuring cylinder, fill test tube 1 with 10 ml of water.Fill the remaining test tubes with 5 ml of water.
3. Using your tweezers, add a single crystal of potassium permanganate to test tube 1.
4. Gently shake the test tube until the crystal has dissolved.
5. Using the transfer pipette, carefully remove exactly 5 ml from test tube 1 and pour it into test tube 2.
6. Rinse the transfer pipette thoroughly to ensure that no purple solution remains.
7. Gently shake test tube 2 and repeat the transfer process, transferring exactly 5 ml of solution from the test tube 2 and test tube.
8. Rinse the pipette again and repeat the transfer process for test tubes 4,5 and 6.