How will I complete my experiment
I will endeavour to find out how the amount of yeast affects the results of an experiment. Firstly I will explain how I will conduct the experiment. For this I will use five different pieces of equipment for the containment and measurement. I will use a test tube, two Retort Stands, a bung with a length of rubber pipe to carry the gas that will be released a basin and a measuring cylinder set up so that when the reaction occurs, It will occur in the test tube, and the resulting gases that is produced if funnelled up the tube, and will displace water out of the measuring cylinder. I will also use three Instruments for the measuring of input and output a stopwatch, (I will record the amount of gases produced every twenty seconds until get two consecutive results that are Identical. And also a set of accurate scientific scales so I can effectively and accurately measure a fifth of a gram of yeast. And a measuring tube to make sure I measure out the correct amount of hydrogen peroxide. The variable that will change will be the amount of yeast. All other possible variables will be kept the same.
I will place the 2H2O2 into a test tube then add the yeast. Getting my partner to push the bung into the top of the test tube to ensure no oxygen is lost as soon as the yeast ands hydrogen peroxide have been combined then I will start the stop watch, every 20 seconds I will record the results. I will test each weight of yeast 3 times and if there are any clear outliers I will record and discount them but still make note so I can try and hypothesise s to why the result was outside the normal parabolas.
To ensure my safety and the safety of those around me I will conduct myself in a manor appropriate for a laboratory, I will ensure that both myself and my partners are wearing safety goggles and that we do not spill any hydrogen peroxide or yeast. I will handle laboratory glassware carefully so as not to break or damage it.
Conducting the experiment
I conducted My experiment with out any unexpected situations, and only one outlying result. below are my results.
`I represented this information into two graphs. The first shows the mean of the results gathered from the experiment with 0.2g of yeast and the second shows the results for the experiment with 0.4 grams of yeast. Both graphs have relatively steady curves but the 0.4g experiment stops reacting earlier, but produces more Oxygen Meaning that the rate of reaction is faster due to the increased amount of the active material catalyse
I believe this is because of the enzymes nature. Because an enzyme is re-useable, the reaction could take place if only one cell of yeast was in the hydrogen peroxide. But this would be incredibly slow, releasing only a few molecules at a time from the substrate so the more cells of yeast the faster the reaction.
But this does not explain why the second graph displays that more oxygen is produced, the catalyse was the only component increased and is only used as a catalysing agent within the reaction. I think that the reason this occurs is because of the method used for recording we recorded every 20 seconds until we got two consecutive results that were the same, then discounted all after that. The Reaction was most probably reacting during this time, but just much slower, as the graph shows a change in speed of reaction as the line is curved not straight the graph plateaus, because the reaction has stopped. No more oxygen is being released but time continues to pass. Also the method could be improved, there will inevitably be loss of oxygen while the bung is placed in the test tube and there is the possibility of the tube, feeding the oxygen to slip out of the measuring cylinder. I think if I was to re-run this experiment I would use this method.
Evaluation
This is my Idea for improvement on the test. It is much more compact. (Numbered on diagram left:1 far left, 2 middle, 3 right) It requires one retort stand with two clamps, one test tube with a bung and one syringe. You insert the measured hydrogen peroxide into the syringe, and place vertically over the test tube, and clamp there (1). You start the stopwatch as you push the syringes plunger down (2). Oxygen produced pushes plunger back up syringe tube giving accurate reading. Measure every ten seconds, until you get 5 consecutive results that are identical. Then repeat 3 times. After you have tested one weight of yeast 3 times move onto the next weight of yeast, to get a wider spread of information I would test more than 2 weights of yeast, I would suggest 0.1g, 0.2g, 0.3g, 0.4g and 0.5g of yeast.
Another suggestion to improve reaction time would be to grind the yeast to a powder, so more surface area is available to react with. And test the speed of the reaction of this against un-ground yeast..
Conclusion
To conclude, I believe that I have found evidence that the increased weight of yeast sped up the production of oxygen but not the volume of oxygen produced as the amount oh hydrogen peroxide stayed constant but nearing the end of the reaction the oxygen was produced in un-measurably small quantities, I consider this an error in the method, because of the way we recorded results it was inevitable that this result would occur. If I was to re-do the experiment I would use my method so as to capture all oxygen, measure it more accurately and not lose any results. And also I would plot the graph in a way that shows how much gas produced since last reading so it displays the peak of the reaction.
Bibliography