The Effect of an Enzyme on the Rate of a Reaction

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Core Practical: Enzyme concentrations and enzyme activity.
Introduction
In this experiment I shall investigate how the enzyme concentration can affect the initial rate of reaction. I will measure the effect of the enzyme in 5 different concentrations against the controlled variable of the reactant. The enzyme which will be used is different concentrations of potato and the reactant used will be Hydrogen Peroxide. Hydrogen Peroxide which will be the buffer solution is a PH of 7.2. My hypothesis for the experiment is that as the concentration of the enzyme is increased the rate of reaction will be increased, producing oxygen at a faster rate. The results in my opinion will show positive correlation. The amount of buffer solution (hydrogen peroxide) will be kept the same throughout the experiment in the interest of reliability and the amount of enzyme (potato) will be decreased as the experiment is carried out and a measurement will be taken as to how fast the enzyme is produced. Variables

The independent variable for this investigation will be the amount of enzyme which will be reacting with the Hydrogen Peroxide solution. I will be using potato as the enzyme in the reaction and the amount of potato will begin at 5ml and decrease by 1ml increments until it reaches 1ml which will be the final measurement. The dependent variable in this investigation will be the rate of the reaction between the enzyme and the buffer solution. According to my hypothesis the rate of reaction will decrease as the amount of enzyme is decreased and the reaction will take longer to produce a particular amount of oxygen as the amount of enzyme is decreased. The controlled variables in my experiment are the amount of hydrogen peroxide which acts as the buffer solution, this is necessary in order to ensure accurate results. The boiling tube in which the reaction takes place will also be kept the same and will be cleaned out with water after each reaction. This is necessary to avoid contamination of the rest of the reactions by surplus potato or hydrogen peroxide. The delivery tube will also be cleaned and kept the same, for the same reasons as the boiling tube. The water which the syringe is collecting the oxygen, will be changed after each reaction and the amount of water will be kept the same, this would not significantly affect the experiment but is controlled in the interest of validity.

The amount of hydrogen peroxide must be kept the same as if the amount were to be changed then the entirety of the experiment would be affected and it would completely compromise the investigation. The boiling tube in which the reaction takes place must be controlled as if it was not then the following experiments could be contaminated by surplus enzyme or hydrogen peroxide. The delivery tube which is used must also be kept the same and cleaned in order to prevent the same contamination as the boiling tube. The water being changed and the amount of water being kept the same would not significantly affect the results of the reaction but is kept the same in the interest of validity.

Method
1. Set up the apparatus: Place the boiling tube in a test tube rack and place the delivery tube’s bung in the top of the tube. Place the other end of the delivery tube in a beaker filled with water, and then place the syringe barrel which is used for collecting the oxygen with the screw clip on the end, over the end of the delivery tube, and this is how the oxygen will be collected. 2. Blend a quantity of potato and place 5cm3 of it in the boiling tube along with 5cm3 of buffer solution. 3. When the hydrogen peroxide solution is added to the potato juice, immediately place the bung and delivery tube firmly into the boiling tube. Place the other end of the delivery tube under the collecting tube. 4. Start a stop clock as soon as the first bubble of oxygen enters the collecting tube from the delivery tube. Collect any gas produced in a three-minute period....
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