• 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
  11. 11

Substances called catalysts can speed up many chemical reactions.

Extracts from this document...


Substances called catalysts can speed up many chemical reactions. Enzymes are biological catalysts and were discovered by the German chemist Edward Buchner. Enzymes can be divided into two groups intracellular and extra cellular. Intracellular occur inside the cell where they control metabolism. The latter are produced by cells but achieve their effects outside the cell they include the digestive enzymes that breakdown food. Enzymes are always proteins and their characteristics therefore reflect the properties of proteins. Their main properties are as follows 1. They generally work very rapidly. The fastest known enzyme is Catalyse. Found in the tissues it speeds up the decomposition of hydrogen peroxide into water and oxygen. 2. Enzymes are not destroyed by the reactions they catalyse and so can be used again. This property can be explained by examining how an enzyme works. When an enzyme controlled reaction takes place the enzyme substrate complex. With their various bonds held in relation to each other by the enzyme the substrate molecules react together to form an enzyme product complex. This splits into the enzyme unchanged by the enzyme and product. The enzyme unchanged by the reaction can be used again. ...read more.


My graph will look similar to this: Average time (S) Temperature (oC) If I decide to draw a graph showing the rate of reaction as well it would look like this: Rate of reaction (S-1) Temperature (oC) I expect that as the temperature increases, the rate of reaction will also increase. I expect the rate of reaction to double with every 10oC rise in temperature. This is because the molecules, which are reacting, move faster and have more energy at higher temperatures. To calculate the rate of reaction I will divide 1000 by the average time. Obtaining evidence The results that I obtained and recorded during the experiment, testing the relationship between temperature and the rate of the reaction of starch and the enzyme amylase, were as follows: Temperature (oC) Time 1 (s) Time 2 (s) Average Time (s) Rate (S-1) 0 1500+ 1500+ 1500++1500+= 3000+/2 =1500+ 1000/1500+= 0 20 900 720 900+720= 1620/2 =810 1000/810= 1.23 30 375 375 375+375= 750/2 =375 1000/375= 2.67 40 260 240 260+240= 500/2 =250 1000/250= 4 50 315 300 315+300= 615/2 =370.5 1000/370.5= 3.25 60 1500+ 1500+ 1500++1500+= 3000+/2 =1500+ 1000/1500+= 0 Interpretation First of all the average time taken for the starch to be digested in each condition was calculated. ...read more.


I aimed to start the stop clock the exact moment the starch and amylase were mixed together, but I may have been a second or two off. 3. Dropper- I used the dropper to measure out 2 drops of iodine. I found this instrument quite accurate but found myself accedently putting in 1 or 2 more drops than required. I think my results are reliable. I believe this because if you look at my table of results the replication of results are similar but not identical. The only replication, which would cause great concern, was the result at 20oC When I plot my results on the graph there did not appear to be any anomalous results all points fell on the line of best fit. Are my results good enough to convince other people? My answer to this question would be yes. I feel that I have enough evidence to convince other people. In the experiment I obtained five separate, accurate readings of how temperature affected rate and I feel that this is an acceptable amount to support my conclusion above. This conclusion proved that as the temperature of the water increased, the rate also increased up until 40 oC and then decreased rapidly. My curved graph shows this trend. Nicholas Killough - 1 - ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & 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 AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    How does the concentration of enzymes affect the breakdown of starch by a-amylase in ...

    4 star(s)

    Notice that the points plotted on the graph are joined up using a straight line. There is a very logical reason for this. This reason is that I simply cannot guess what the diameter of the clearance rings is going be at concentrations in between 0% and 2%, 2% and

  2. For this investigation I am going to investigate the effect of the concentration of ...

    be more active sites available for the starch to be broken up in but if there is enough substrate to occupy all the active sites on the enzymes then the rate of reaction will not change and for this reason I will use the same volume and the same concentration of substrate for all of the experiments.

  1. Experiment to Investigate the Effect of Copper Ions on a Solution of Amylase and ...

    Once the water bath had reached 60°C the three test tubes were placed into the water bath. 7. Thermometers were placed into each of the test tubes to monitor the temperatures of the 3 solutions. When the solutions had reached 60°C they were mixed and at the same time a stop clock was started.

  2. 'Investigating how temperature affects the rate action of the amylase enzyme on starch.'

    One other beaker will have cold water and the last will contain hot water. This is simply needed to maintain the temperature and so If it was to decline then hot water would be added to restore back the temperature and vice versa.

  1. Investigating the Rate of Reaction of the Enzyme Amylase on starch

    starch solution Starch 2% 2% of 30 = 0.6g Therefore I must mix 0.6g of starch powder with 30cm3 of distilled water to make a 2% starch solution Starch 1% 1% of 30 = 0.3g Therefore I must mix 0.3g of starch powder with 30cm3 of distilled water to make

  2. Catalyse Investigation

    This happens fastest at pH 5. At a higher pH level than pH 5 the time taken for the amylase to digest the starch increases. Amylase speeds up the breakdown of long chain starch molecules into smaller chains of maltose. Enzyme molecules have a very precise three-dimensional shape.

  1. Investigation on starch and the enzyme amylase.

    This being all stated in the background research above. For my second problem, I predict that as the temperature increases, the rate of reaction will also increase. This being due to the kinetic theory, which states that heat makes the molecules vibrate causing them to collide with each other.

  2. "Enzymes are biological catalysts, which increase the rate of chemical reactions within living cells. ...

    Taking into account that there is the same amount of catalase, this means that more hydrogen peroxide molecules will be bound to the active sites of the catalase every second. This will increase the enzyme activity as there will be more active sites being used, and therefore the increase in

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