My prediction is that the higher the concentration of glucose present in the experiment the faster the reaction will take place. The reason the reaction will go faster is that if there is a higher concentration of glucose there are more glucose molecules to break down the potassium ones. To test this prediction an experiment must be carried out, changing the concentration of glucose each time.
Equipment list
- Ten boiling tubes
- Stop clock
- Several syringes
- 2 Boiling tube racks
- Potassium permanganate
- Glucose
- Water
- Sulphuric acid
Diagram
Plan
In order to test this prediction, ten boiling tubes must be taken and each filled with 5cm³ of bench strength sulphuric acid, and 2cm³ of bench strength potassium permanganate and then a mixture of glucose and water.
To test the different concentration theory, in one tube 1cm³ of glucose and 9cm³ of water must be added, then in the next one 2cm³ of glucose and 8cm³ of water, and so on until there is 10cm³ of glucose and none of water. From the second the last syringe of glucose is added to the solution in the last test tube the timer must be started. The time must be measured for each tube to turn colourless. From this it will become apparent whether the prediction was correct. A table of results must be drawn to finalise this prediction. To keep the experiment fair, the same amount of potassium permanganate should be placed in each tube and the same amount of sulphuric acid as well. The only variable in the experiment is the concentration of glucose-water solution. The experiment should be conducted at room temperature.
Results
Conclusion
Having looked at theses results, it is clear that my prediction was correct. There are no anomalous results that I can see. The more glucose there was in the solution the faster the reaction took place.
Evaluation
This experiment worked fairly well, however there were many areas which may have affected the accuracy of this experiments results, for example, the equipment used for this experiment was not 100% or in fact anywhere near 100% accurate, for example the syringes used are quite short and fat, so there is a 10% chance of error when measuring the water level, this is because it is hard to tell when the water level has exceeded the desired amount. Also the meniscus effect on the water level must be taken into account. Tension on the surface of the water causes it to magnetically attract to the sides of test tubes and syringes making it difficult to measure the exact water level. Also if the syringe is not viewed at eye level then the actual amount measured can differ by up to 1 cm³. Also it is hard to say exactly when the solution has gone completely colourless. If the experiment could be done again with more accurate equipment then the results could possibly be very different. If there was some way to measure the amount of light that passes through the solution, then it would be easier to tell when the solution had gone completely colourless. There were no anomalous results in this experiment, though that may be due to inadequate equipment.
