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Plan an Experiment to Investigate the Effect of pH on Immobilised Yeast Cells on the Breakdown of Hydrogen Peroxide.

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Plan an Experiment to Investigate the Effect of pH on Immobilised Yeast Cells on the Breakdown of Hydrogen Peroxide. Safety: o Extreme alkaline and acids are used so must wear gloves, goggles and apron. o Be very careful not to make contact with any of the chemicals, as they will be irritable and some corrosive to the skin and eyes. o There must be no running and any other normal laboratory rules should be followed as usual. o Hydrogen peroxide is corrosive and so should not be touched. o A lab technician should immediately wash up spillages. o Always be careful of the glass instruments as these could break. Background knowledge: In my experiment I will be measuring the amount of oxygen given of in a gas syringe over a certain time period from different pH levels. Hydrogen Peroxide is a chemical compound, H2O2, a colourless, syrupy liquid that is a strong oxidizing agent and an in water solution a weak acid. It is miscible with cold water and is soluble in alcohol and ether. Although pure hydrogen peroxide is fairly stable, it decomposes into water and oxygen when heated above about 80�C; it also decomposes in the presence of numerous catalysts e.g. ...read more.


The pH will be changed using a range of buffer solutions, which is explained above in the background knowledge. Dependant Variables: All the other variables have to be kept constant throughout so that the results from the changing independent variable can be accurately measured. As if the dependant variables temperature, enzyme concentration, substrate concentration etc change then this will cause irregularities in the results. So therefore the experiment would be inaccurate and not useful for the investigation. The dependant variables are explained and bulleted below: o Temperature should be kept constant. This is because an increase I temperature causes more collisions and an increase in rate of reaction. So if one test-tube result is measured at a different temperature to the others it will be irregular as it will be working faster if it has a higher temperature or slower if it was a lower temperature. So in my experiment I am going to use a water bath set to be at 30�, which is just off room temperature. o Enzyme (Catalase) and Substrate (Hydrogen Peroxide) amounts need to be kept constant. This is because if one test-tube had more enzymes (alginate yeast) and substrate it would have more active sites and a higher chance (probability) ...read more.


Now rapidly inject the 5ml of hydrogen peroxide into the test-tube 1 and immediately place the bung on and start the stopwatch. o On your results table using the stopwatch record the figure every 30 seconds for the amount of oxygen delivered into the gas-measuring syringe. Do this for 120 seconds (2 minutes) and then stop. o Return gas syringe to 0 after removing the test-tube for the next measuring of test-tube 2. o Using a sieve remove the 50 beads and wash them using distilled water. o Once cleaned properly place beads into test-tube 2. o Repeat procedure of test-tube 1 for test-tube 2 except with a buffer solution of pH 3. o Keep repeating the procedure changing the pH of buffer solution by increasing it by 2 each time until u get to pH 13, which is the end. o Repeat the experiment four times and work out an overall average of all 15 results for each pH 1, 3, 5, 7, 9, 11, and 13. o Then put these results into suitable graphs. Results Table: pH 1 ph 1 pH 1 pH 2 pH 2 pH 2 pH 3 pH 3 pH 3 pH 5 pH 5 pH 5 pH 7 pH 7 pH 7 pH 11 pH 11 pH 11 pH 13 pH 13 pH 13 Time (seconds) Volume Of Oxygen Gas Produced (ml) 30 60 90 120 OJ Wilson AS Level Coursework ...read more.

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