Serial Dilution

 Aim: To make a dilution series to investigate concentration.

Hypothesis: I think that the potassium permanganate will slowly dilute as we tip 5 ml of every test tube into the next test tube.

Equipment:

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

Method:

1. Place 6 test tubes in a test tube rack. Label the rack with numbers 1-6
2. Using the measuring cylinder, fill test tube 1 with 10 ml of water. Fill the remaining test tube 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 test tube 2 to test tube 3.
8. Rinse the pipette again and repeat the transfer process for test tubes 4, 5 and 6.

Discussion:

Which was most dilute? Test tube 6

Least diluted? Test tube 1

Most concentrated? Test tube 1

Least concentrated? Test tube 6

How fo you know? With the most diluted the colour of the liquid has less colour to it and the most concentrated is the brightness of the liquid.