• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10

Decomposition of Hydrogen peroxide

Extracts from this document...


Decomposition of Hydrogen peroxide SCIENTIFIC BACKGROUND INFORMATION I will investigate the factor that affect rate of reaction of the enzyme catalase. Catalase is an enzyme found in living cells i.e. potato and liver. It promotes the conversion of hydrogen peroxide a powerful and potentially harmful oxidising agent to water and molecular oxygen (the enzyme increases the rate of decomposition of hydrogen peroxide into water and oxygen). The reaction is: - 2H O --> 2H O + O Enzymes are biological catalysts that increase the rate of a reaction. The reactant substances upon which an enzyme acts are termed the substrates. The substances produced as a result of the reaction are the products. Enzyme-controlled reactions are mostly reversible and involve the formation of an intermediate enzyme-substrate complex. Activation energy In order to start a reaction, chemical bonds must be broken so that new bonds can be formed. The energy necessary to break these bonds is the activation energy of the reaction. The graph below shows changes, which will take place when hydrogen peroxide breaks down to produce water and oxygen. One way in which we can provide the activation energy to start this reaction is to add an enzyme (catalase) Catalase lowers the activation energy and, as a result, the reaction will take place at the much lower temperatures found inside the cells of living organism Catalase will speed up the process because the enzyme lowers the activation energy of the reaction. This means that the free energy required for the reaction to take place will be made smaller by the presence of catalase. In fact, catalase is particularly reactive enzyme. ...read more.


When all the active sites are occupied and the amount of enzyme is the limiting factor, as you increase the amount of the substrate there are more collisions and more enzyme- substrate complexes formed. If the temperature increases, it can affect the rate of an enzyme-controlled reaction in two ways: (1) As the temperature increases, the kinetic energy of the substrate and enzyme molecules increases and so they move faster. The faster these molecules move, the more often they collide with one another, and therefore the rate of reaction is faster. In addition, the more often they collide more enzyme- substrate complex is formed and more products are released. (2) As the temperature increases, the more the atoms, which make up the enzyme molecules, vibrate. If they vibrate, too much it will break the hydrogen bonds and other forces, which hold the molecules in their precise shape. The three-dimensional shape of the enzyme molecules is altered so much that their active sites no longer fit the substrate. The enzyme will be denatured and loses its catalytic properties. The optimum temperature for an enzyme varies considerably, depending on its surroundings. For many enzymes, the optimum temperature is 400C and denaturation occurs at 600C. Altering the pH can also break the bonds of the three-dimensional molecular shape. This is because the bonds may be broken by the concentration of hydrogen ions and pH is a measure of hydrogen ion concentration. Any change in the pH can denature enzymes. Each enzyme work best at its own particular pH (Optimum pH). Changing the size of the surface area of the potato can also alter the rate of reaction. ...read more.


had to use the same cork borer, it was very difficult to obtain a piece of potato tissue, as each time you use cork bore you had to cut it straight down, not on the side. Moreover, I had to maintain the same surface area of the potato tissue, sometimes, though; you have used the same cork bore, I difficult to have the same diameter of the potato tissue (every time to void some errors I had to cut the straight down). It was difficult to maintain the same level of temperature, as when the reaction is rapid the substrate concentration is high and energy will be released, which might have increase the temperature of the hydrogen peroxide. In addition, I should have measured first the room temperature, as this might have effect on my results. Moreover, since rates of reaction are so sensitive to temperature I still would have liked to use a water bath during this experiment, as this would have regulated the temperature. When starting the reaction by adding the hydrogen peroxide and the potato together they reacted immediately so I had to quickly put the bung in very quickly. When I was doing, this some of the oxygen may have escaped before I put the bung in. This would have directly affected my results and therefore my accuracy. I could not start the timer and put piece of potato into the hydrogen peroxide at the same time therefore the timing was a bit inaccurate. I would have been better if I had had a partner to start the stop clock for me once the potato tissue was introduced to the hydrogen peroxide. This may have improved my results slightly. ?? ?? ?? ?? Ali Ahmed ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Life Processes & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Life Processes & Cells essays

  1. Marked by a teacher

    effects of substrate concentration on the activity of the enzyme catalase.

    4 star(s)

    worked however, the reaction was a bit too slow. So I have decided to time how long for 5 cm� of gas to be collected and not 10cm�. The temperature and PH are unchanged by the reaction so they would not have to be controlled.

  2. To investigate the effect of enzyme concentration on the activity of catalase in potato ...

    Average time graph: From this graph you can see that as the surface area/number of potatoes increases the average time taken to produce 5 ml O2 decreases. For example the average time taken for 1 potato is 98 seconds but for 2 potatoes it is 39.33 seconds.

  1. Investigating the effect of enzyme catalase concentration on hydrogen peroxide.

    in then as there is more substrate to react with the number of bubbles produced increases since there is more substrate available to the active binding sites. Then the curve begins to drop ever so slightly. This drop can be explained since there should be a point when the number

  2. An investigation into the effect of substrate concentration on the activity of the enzyme ...

    10 0 4.8 9.1 - - - 127 8 2 4.4 8.6 - - - 140 6 4 3.9 7.9 9.6 - - 185 4 6 3.7 6.4 8.7 - - 199 2 8 2.6 4.7 7.3 9.5 - 278 0 10 0 0 0 0 0.1 - Set 3 Volume of Hydrogen Peroxide (cm�)

  1. Inhibition of the decomposition of hydrogen peroxide by the catalase enzyme using copper sulphate.

    catalyses the break down of hydrogen peroxide in to water and hydrogen gas to the best ability. Preliminary investigation to find the best available catalyst. Aim: To find to the root vegetable that contains the highest level of the enzyme Catalase using the decomposition of hydrogen peroxide.

  2. Investigate the effect of enzyme concentration on the activity of catalase in potato tuber ...

    The surface area is a measure of the amount of enzyme that is in contact with hydrogen peroxide. So as there is an increase in the number of potatoes so there is an increase in surface area of the potato.

  1. An investigation into how enzyme concentration (catalyse in a potato) affects the rate of ...

    To improve the experiment, I could have measured shorter intervals, for a longer time with more variations of the concentrations of the solution. It also would have been a good idea to wash the equipment more thoroughly before starting the next test.

  2. For my coursework I will be performing an investigation into an experiment using hydrogen ...

    Method for Preliminary Experiment 1. I used all of the apparatus below, and set it out as shown in the diagram. Apparatus * 1x - Knife - for cutting up the potato * 1x - Ruler (mm units) - for measuring the length of the potato * 1x - Ceramic

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work