Making a dilution series

When comparing solution, it is important to know how much solute has been dissolved in the solvent. Scientists use the terms dilute and concentrated to describe how 'strong' a solution is.

A dilute solution contains a small amount of solute. At home, if you were to make a 'weak' coffee, in scientific terms you are making a dilute solution of coffee.

A concentrated solution contains a large amount of solute. At home, if you were to make a 'strong' coffee, in scientific terms you are making a concentrated solution of coffee. 

Aim: To make a 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 test tubes in a test tube rack. Lable 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 tub 1.
4. Gently shake the test tube until the crystal has dissolved.
5. using the transfer pipette, carefully remove exactly 5ml from test tube 1 and pour in 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.

Observations:
During the experiment, as we added the liquid from test tube 1 into test tube 2 it started to get lighter and slowly started to lose its colour as we added it to all the other test tubes.