Making a Dilution Series (Concentration)

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 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 tubes with 5 ml of water.
3. Using your tweezers, add a single crystal of potassium permanganate to test tube one
4. Gently has the test tube until the crystal has dissolved
5. Using the transfer pipette, carefully remove exactly 5 ml from test tube one and pour it into test tube two.
6. Rinse the transfer pipette thoroughly to ensure no purple solution remains.
7.  Gently shake test tube two and repeat the transfer process, transferring exactly 5ml of solution from tube two to tube three.
8. Rinse the transfer pipette again and repeat the transfer process for tubes four, five, and six

Results/Discussion:

While my group was doing the experiment, we first put the correct amount of water in the tube. We then took a small amount of potassium permanganate and dissolved it into our water. Next, we needed to transfer the solution. Because we didn't have a pipette that measured exactly 5mL, I thought, "hey, this is a 3 mL pipette, what if we did two sets of 2.5? And it worked! While doing the experiment, we realised that it started out a dark purple but then the colour was getting lighter and lighter. My theory is that the excess water was diluting the purple colour.

 During the experiment, I told Jakita what to do while Ella took photo's

Conclusion:

When we finished the experiment, we were left with six tubes, with the liquid in each getting lighter and lighter. Apparently, this is what was meant to happen, so I'll consider this a success!

After the experiment, Jakita and Ella mixed all the solutions together and put it in the sun.