The Effect of Surface Area on the Rate of Reaction Between Catalase from a Potato and Hydrogen Peroxide

The Effect of Surface Area on the Rate of Reaction Between Catalase from a Potato and Hydrogen Peroxide
Aim To find out the relationship between the surface area of a potato chip and the rate of reaction when hydrogen peroxide is put in with it. Variables As I do this experiment the thing I am going to be changing is the surface area of the potato chip, first I will put it in the beaker as a whole (3cm chip) then I will start cutting it into smaller pieces and repeating the experiment. I will keep the temperature the same throughout all the experiments also I will keep the amount and concentration of hydrogen peroxide the same, the amount of potato and the same brand of potato. By doing this I will make it a fair test. Prediction I predict that the bigger the surface area the quicker the 10 cubic cm of hydrogen peroxide gas will be produced. I think this because as the surface area increases, the speed of the reaction will increase therefore the gas will be produced faster. I believe this because most chemical reactions happen faster when there is more of the reactant to react with. When there is a larger surface area, there is more of the reactant available, which makes it easier for them to react together. Usually, when the surface area is doubled it will double the rate of reaction. Chemical reactions take place by chance. Particles need to collide with enough velocity so that they react and interlock with each other, this is called the lock and key theory. As the surface area is increased the particles have a bigger surface to react with so more molecules can react at a time. This means that they are colliding more often and there is a bigger chance that the collisions have enough velocity to cause a reaction. Since there are more collisions the chemical reaction takes place faster. What am I measuring? I am measuring how long it takes to collect 10 cubic cm of gas in a measuring cylinder when the surface area of the potato is multiplied. Number of readings I will be repeating this experiment twice or maybe three times on anonymous results to make sure I am getting the most accurate result I can. Range The range of potato will be form a whole (3cm chip) to slices of a sixth of a 3cm chip. This will be done by measuring the chip with a ruler and cutting it into equal parts. Method First my partner and me got out apparatus and set it up as shown below. We then put safety goggles on to protect our eyes and filled up the syringe with 20ml of hydrogen peroxide. Then we put a 3cm chip of potato in a beaker and blocked the top off with a cork. We then put a measuring cylinder into the water and made sure it didn?t have any air bubbles in it, we stood it up slanted in the water so there was a gap to fit the rubber tube. Then we fixed the syringe to the tube of the beaker and squirted in the hydrogen peroxide, we waited a few seconds for the air to come out of the tube and then we put it into the measuring cylinder. Gas was coming out of the beaker from the reaction with the potato and going through a tube into the measuring cylinder. After all the air was out we started the stopwatch, and waited to see how long it would take to fill 10 cubic cm of the cylinder. We then repeated the same experiment but made the surface area of the potato bigger. Results Amount of potato Time 1 (secs) Time 2 (secs) Average (secs) Whole 390 362 1.07 Half 288 242 1.19 Third 238 228 1.04 Fourth 130 260 (anomalous) 153 0.84 Fifth 105 113 0.92 Sixth 70 75 0.93 Analysis Conclusion I have come to the conclusion that as the surface area of the potato gets bigger the rate of reactions gets faster (the quicker 10 cubic cm or gas is produced). This happens because as the surface area increases, the speed of the reaction will increase therefore the gas will be produced faster. I believe this because most chemical reactions happen faster when there is more of the reactant to react with. When there is a larger surface area, there is more of the reactant available, which makes it easier for them to react together. Usually, when the surface area is doubled it will double the rate of reaction. Chemical reactions take place by chance. Particles need to collide with enough velocity so that they react. As the surface area is increased the particles have a bigger surface to react with so more molecules can react at a time. This means that they are colliding more often and there is a bigger chance that the collisions have enough velocity to cause a reaction. Since there are more collisions the chemical reaction takes place faster. Evaluation My results are quite accurate but I did get one anomalous result, this was probably because on the previous experiment I didn?t wash out the beaker properly, a human error. One thing I saw which could be improved is that I had to keep the hydrogen peroxide moving over the potato so that all the potato go a fare share of the hydrogen peroxide. This could perhaps be improved by putting more than 20ml in so the whole potato is covered or by using smaller equipment. Another thing is that the room temperature varied, in that as more people came in the room the temperature rose, so this could make the experiment go faster. I could also make improvements by comparing my results to others in the class and seeing what they got.

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