Year 13 students have been completing experiments as part of their A Level Chemistry syllabus which have included analysing the rate of chemical reactions and making and testing aspirin then comparing the results against store bought samples.
A total of 32 students took part. Mr Knight said: ‘There is an aspirin experiment and the others are kinetics type experiments where the students have chosen a reaction and they are finding the mechanism of the reaction. They are going to find the rate constant then they are going investigate the effect of temperature to determine the activation enthalpy and then they are going to repeat the experiment with a catalyst to find out how the catalyst might lower the activation enthalpy and hence why it makes the reaction so quick.
‘The students have had to design their investigation and solve problems to develop a working method. They are not allowed to sit down when they are doing the experiments for safety so they are on their feet all the time which can be tiring for them.’
Anya Scoular said: ‘I am doing an iodine clock where you have to react two solutions and keep stirring and measuring the temperature and they will turn from colourless to blue when the reaction is complete. I am using potassium iodide and potassium peroxide and there is also sodium disulphate and starch in there so the starch is the indicator that turns it blue.
'My measurements are going all right. Today is slightly easier because they are all the same concentration in each testube whereas yesterday each three was a different concentration so you kept having to vary the concentrations. We did preliminary experiments last week. This is the fun bit, but three days standing on our feet is hard!’
Gautham Kumar said: ‘I am finding the rate orders of the reaction between hydrogen peroxide and three different catalysts. Right now I am using potassium iodide but I am also using manganese dioxide and a yeast catalyst. I am finding how temperature affects the reaction and also how different catalysts affect the rate. It is going pretty well and I am slightly ahead of schedule. I have got some of the theory already in place and these results are roughly what I would expect.’
Julia Komor said: ‘I have made three samples of aspirin so far and the entire point of the experiment is to synthesise three samples of aspirin, each using a different method and then comparing them to a sample of store bought aspirin. You use three different methods to compare them in terms of purity and you try to find a method that yields the optimum results.
‘You have to combine salicylic acid with ethanoic anhydride. You use sulphuric or phosphoric acid to catalyse the reaction and basically you have to stir and filter it and you have got a white powder. Aspirin has a very precise melting point so if the sample is above or below that then it is impure. I am enjoying the process. It is a long time and taxing but it is very enjoyable. I have had some minor problems and had to restart a couple of times but there weren’t any major setbacks so it has gone quite smoothly.’
Head of Science, Mrs Hearne said: ‘This is excellent preparation for studying science at university as the students have had to work independently to plan and carry out more complex practical work. They now have the task of analysing and evaluating all the data that they have generated during the three days to complete their coursework.'