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This is decomposition reaction because the H O is breaking down to simpler H O + O H O forms in cells this is toxic and must be removed rapidly. Catalyse catalyses the breakdown in cells. Potato cells contain catalyse enzymes.

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Introduction

INTRODUCTION I am investigating how surface area affects the rate of oxygen production when a potato is placed in a solution of hydrogen peroxide. This experiment between hydrogen peroxide and the potato which contains an enzyme which is a catalyst will allow me to clearly see the effects to rate of oxygen production as surface area is changed. Reaction 2H O O + 2H O From previous work and my scientific knowledge I know these factors affect rate of oxygen production: 1) Surface area (the factor I investigated) 2) Temperature 3) Concentration Investigating how surface area affects oxygen production because I felt it would give the clearest answer on how rate of oxygen production is affected by surface area, also from previous knowledge I believe the results will give me wider scope for analysis and evaluation. I chose to use a range of surface areas between 2 ends of cylinder and 64 ends from the potato cylinder. This range will allow me to get a wide spread of results and allow me to see any changes clearly and get a deep understanding of how oxygen production is affected. These are the steps I took to make sure that all conditions fair and to keep all variables constant also to insure the results were clear and correct. ...read more.

Middle

The diameter of the potato cylinders is about 6mm. Then lay all the cylinders and cut them to the same length, the length of the shortest cylinder. The length should be no smaller then 40mm. Now 2 cylinders are cut in half to give two pieces, 2 cylinders are cut into 4 equal pieces; another 2 are cut into 8 equal pieces. Another 2 are cut into 16 pieces with another 2 into 32 pieces, 2 are left uncut. A scalpel is used to cut the potato cylinders. To make sure all pieces are equal measure with ruler. Measure 4cm of hydrogen peroxide accurately into the graduated test tube. After this is completed the stopwatch is checked to see if the timer is reset. Once this is done and the equipment is in place it is ready for the experiment. The potato cylinder is put into the acid and the timer is started, every 15 seconds the amount of oxygen produced is measured using the graduated test tube and is recorded. This is done for two minutes every 15 seconds then the timer is stopped and all results are recorded. Once the experiment is completed and the graduated test tube is washed and dried and the experiment is repeated for each different surface area twice. ...read more.

Conclusion

Error of graph plots = 0.5 x 10 -2 X 100 =12.5% 4.0 x 10 -2 Accuracy of Graph = diff X (1000) Avg. value PROCEDURAL ERRORS ==> Reaction time of hand-eye - error of 0.1s (automatic timer by laser) ==> Not all the bits of potato are in the acid when timer is started - error 5% (automatic stirrer) ==> The potato may have lost some of the catalyse (Use newly grown potato) ==> Judging accurately the amount of O produced. (automatic detector) ==> Temperature not always being the same (measure and control temperature) INSTRUMENTAL ERRORS ==> Measuring cylinder 7cm error in 0.5cm - 2% error ==> Length of potato (4cm) error of 1mm - 2.5% error (metal ruler) ==> Time over 10s error 0.1 - 1% error (automatic) ==> Temperature 2 C, error due to it being not being able to be kept constant 5% ==> Whether equipment is washed and dried properly - 2% Total percentage of maximum possible errors is 17.5% OTHER EXPERIMENTS ==> More results at each surface area - to get a better average ==> Use higher and lower lengths of potato see effect on rate. ==> Use higher and lower concentrations (such as 0.1, 2.2, 5) - to see how concentration affects rate of oxygen production ==> Use other enzymes such as lipase and protease ==> More and less amount of acid ==> At different temperatures ==> Using catalysts ...read more.

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