Experiment 3: Redox Titration

Objective: to determine the minimum amount of MnO4 necessary to make a reaction with potassium.

Materials:

- Burette.

- Clamp.

- Erlenmeyer flask.

- Vertical stand.

- Measuring pipette.

- Test tube with Sulphuric acid (2 M).

- Potassium permanganate.

- Oxygenated water.

Method:

1. Set up the materials as shown in the image below(place the clamp on the stand and attach the burette to the clamp).

2. Pour the permanganate into the burette carefully (make sure the stopper of the burette is horizontal before doing so). It would be fitting to fill it up untill 1 instead of 0 as the compound we are using is really dark and it’s very difficult to adjust it to 0 as you can’t see the number clearly.

3. Put a beaker below the burette and open the burette letting some KMnO₄ pass through until the bottom part of the burette is filled.

4. Adjust the level of potassium permanganate up to 1.

5. Use the pipette to take 10 mL of oxygenated water (H202) and pour it into the 100 mL Erlenmeyer flask.

6. Call your teacher and ask him to add some 2M Sulphuric acid (HCL) to the H202.

7. Place the Erlenmeyer flask under the burette and slowly, let the KMnO4 pass through, while doing this, shake slightly the flask.

8. Repeat the process in step 7, until the solution remains purple when mixed with the KMnO4.

9. Place the stopper in a horizontal position, and record the level of KMnO4 in the burette.

And now a couple videos explaining the procedure and the different results you can obtain from this experiment:

Video 1: the procedure of the experiment.

Video 2: the different results you can obtain in this experiment.

Video 3: redox reaction between HCl, KMnO4 and H202.

Video 4: explanation of the redox equation

CONCLUSION:

At first, we thought that we will need more KMnO4 in order to see the reaction happen but as we performed the experiment, we saw that the amount of KMnO4 needed was not higher than 26 mL. Maybe, for that reason, the fact we thought that more KMnO4 was needed, we added two much and the second reaction (when it turns into a brownish colour) took place far too fast. 

In addition, we think that if we weren't running out of time when we performed the final part of the experiment, we could have had obtained a more accurate result because we would have had time to pour the KMnO4 slower to see when the reaction exactly happened.

Either way, we reached a good result as the amount of KMnO4 needed to make the reaction happen was 25,5 mL and we used 26,6 mL, so it is a good result indeed.