Serial Dilution

Welcome to another Blog-post, On Monday in Science we were learning about concentrated and dilute. 

We also did an experiment to investigate more about concentration and dilution. For this experiment we needed a solvent and a solute. 

The solvent that we used was Water and the solute was Potassium permanganate. 

A solvent is the substance in which the solute dissolves. Solute is the substance being dissolved. 

• 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, 10mL measuring cylinder.

Method: 

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

Results:

As you can see in the photo the colour purple get lighter and lighter as it goes past each test tube. That is because the last few test tubes had more water which means that there was least amount of potassium permangante.  

The test tube that is light purple has least potassium permanganate, most water, which means 

most dilute =least concentrated

Therefore the dark purple test tube has most amount of potassium permangante, least amount of water which means 

most concentrated = least dilute.