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The aims of this experiment are to observe how varying strengths of Hydrogen Peroxide (substrate) increase or decrease the rate of oxygen production when added to a yeast solution.

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Introduction

Decomposition Of Hydrogen Peroxide: The aims of this experiment are to observe how varying strengths of Hydrogen Peroxide (substrate) increase or decrease the rate of oxygen production when added to a yeast solution. Equipment needed... Test Tubes and rack Hydrogen Peroxide of varying concentrations (H) Yeast Solution (H) 1cm� Pipette Burette Syringe Plastic Tub Stopwatch Notepad Goggles Lab Coat Beaker Retort Stand Delivery tube with secure bung Using all of this equipment to the highest level, I can assure that all of my readings are thoroughly accurate and that no anomalous results will occur. Due to the dangerous nature of firstly, the Hydrogen Peroxide, and secondly the yeast (Both of which if spilt in eyes or ingested could prove very dangerous, even deadly), I am using safety goggles and a lab coat as preventatives against spillages and breakages, and using a pipette and syringe to handle the dangerous liquids effectively, safely, and with the maximum efficiency. I will also label each of the bottles very clearly, and adhere to all simple lab rules, e/g/No bags on floors, coats on chairs, no running, and no bags on any work surfaces. There are many other ways that I could have carried out this experiment, such as using different equipment etc; here is why I chose the equipment listed above: Any measuring cylinder only measures accurately to app. 0.5 cm�, but the burette that I am using measures to 0.1 cm� for a lot more accurate reading. I could have simply counted the bubbles, but I did not know what volume each bubble was, hence I am using the burette to measure the volume produced. Diagram Of Equipment: The equipment was set up as shown in diagram above. In order keep this experiment as fair as humanly possible, I am going to take the following steps to ensure complete fairness at all times, and ensure that all other latent variables are kept at a constant level. ...read more.

Middle

The Collision theory states that a chemical reaction can only occur between particles when they collide (hit each other). Particles may be atoms, ions or molecules. There is a minimum amount of energy which colliding particles need in order to react with each other. If the colliding particles have less than this minimum energy, then they just bounce off each other and no reaction occurs. This minimum energy is called the activation energy. The faster the particles are going, the more energy they have. Fast moving particles are more likely to react when they collide. You can make particles move more quickly by heating them up, (raising the temperature). Secondly I believe that all of my predictions are correct, following information gained from "Biology For Life" By M.B.V Roberts, concerning active sites and timings. When I observe the readings on the burette, I am going to repeat this experiment 3 times, but if my results appear inconsistent then I will keep repeating them until I have 3 similar readings to gain averages from. This so that any anomalies can be discarded and retaken, until correct averages can be taken. For this experiment I also used knowledge gained from my preliminary work, with potato chips concerning masses. I found that when a potato was placed in Hydrogen peroxide and left, it began to react. I saw bubbles, which made me decide to collect the give me a means of measuring the reaction. I didn't want to simply count the bubbles as they were all different sizes and I did not know how much of the gas each one contained. I could have used an upside down measuring cylinder to measure the gas content, but it is only accurate to 1.0cm�, so I therefore decided to use a burette, which is accurate to 0.1cm�. Here are the Tables that I have recorded from undertaking my experiment. ...read more.

Conclusion

* Ensure that no oxygen is left in the burette. * Dry all of the test tubes before experiments begin. * Do not let oxygen escape through bungs or any un-noticed holes. * Squirt in yeast in at same pressure each time to ensure they all have the same kinetic energy when they heat the beaker sides and osmosis begins. * Make sure that delivery tubes are all the same length so that oxygen does not have further to travel before being recorded by timer in burette. * Keep Humidity the same throughout all the expts. * Use a mechanical pipette to measure out solutions. All anomalies are explained above, as directed. Using the experiments that I have carried out, I can now make a solid, firm conclusion based on evidence obtained, and that is that Rate of reaction ? Concentration, this can be seen in all of my tables (anomalies aforementioned), my graph and in my preliminary work from all text books, and internet sites listed in my bibliography. To say that the catalyst yeast's reaction is sped up by a substrate is all well and good, but to support a firmer conclusion I will need to undertake more experiments to gain more evidence, to ensure that all of my work is valid and not anomalous, as methods such as using a buffer tablet to control the PH level do not always work. Further Experiments-Extension: If time permitted me to, then I would now test out different substrates on this catalyst. I could simply change the substrate, or I could dramatically change the concentration to see if they were in line with my original predictions made in the first experiment. With my previous experiment with H2O2 I could not get readings with the higher concentrations as they used up the oxygen too fast in the burette and I couldn't get a reading. Using a very large burette could combat this. I could use dilute hydrochloric acid with the yeast to observe how that affected the timings of all the experiments. These may be undertaken at a later date. ...read more.

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