Investigating the Effects Catalyse Has on Hydrogen Peroxide Solution
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Aim: I am going to investigate the effects which catalyse has on a
hydrogen peroxide solution
We would use potato to do the experiment because we had done a
previous experiment when we put a piece of potato and liver into a
hydrogen peroxide solution and the rate of reaction for the liver was
too fast to measure and time. But the potato had a slower reaction
which will be easier to time and we can measure the size of the froth
using a ruler.
Enzymes are special shaped protein molecules which act as catalyst and
work in living organisms. Enzymes help speed up the rate of reactions.
Each enzyme has a unique 3D shape which means that they work with
certain types of substrates. This is also known as ‘lock and key’
because the shape of the substrate fits into the shape of the enzyme,
just the way a lock and key do. Enzymes work by attaching itself to
the substrate molecule. The substrate molecule brakes down where the
active site is. The substrate molecule splits and the enzyme is left
unaffected. The factors that affect enzymes are: temperature, pH and
surface area. Enzymes are used in everyday life because all living
things produce enzymes. Saliva in a human produces a lot of enzymes
for digestion. The optimum temperature for these enzymes to work in is
37.5 °C. Enzymes also perform best at a pH which is around neutral.
When an enzyme reaches 40°C it becomes denatured. Enzymes are also
used in industry e.g. bakery, cheese making, starch processing and
production of fruit juices and other drinks
The substrate splits
This is a graph to show the rate of reaction of enzymes due to
graph showing effect of temperature
I predict that the potato cylinder with the diameter of 10mm will
react faster than the potato cylinders with diameters 5mm and 8 mm.
The reason I predict this is because it has a larger surface area
which means that it contains more enzymes, therefore there should be a
faster rate of reaction.
· Measuring cylinder
· Hydrogen peroxide solution
· Potato borer
· Spotting tile
· Place a potato on a spotting tile and use the borer and bore it into
· Extract the potato.
· Use a ruler to measure the length of the extracted potatoes then cut
it so the potatoes are all the same length which will be 20mm.
· Pour 75ml of hydrogen peroxide solution into a beaker.
· Pour 10ml of the solution into a measuring cylinder.
· Afterwards, drop the potato cylinder into the solution
· Time the rate of reaction using a stop watch per minute for
10minutes and measure height of froth every minute.
This process will be repeated 3 times with potato cylinders with
diameters of 5mm, 8mm and 10mm.
The factors which I would not change are:
· the time the potato cylinder is in the solution
· the volume of hydrogen peroxide solution
· The length of potato cylinders
· The variety of potato
The reason I would not change these variables is so that I can make
the experiment a fair test.
The variable I will change is:
* [IMAGE]The diameter of the potato cylinder
The reason why I am changing this variable is because I want to see if
the hydrogen peroxide solution will react if there are more or less
The graph I produced showed me that the potato cylinder with a
diameter of 8mm reacted faster than the potato cylinders with a
diameter of 5mm and 10mm. The pattern I see is that the reaction keeps
on increasing. The graph I produced to show my results was a curved
line graph because the pattern of the results produced a curve. My
results did not agree with my prediction because I predicted that the
10mm potato will react the fastest but instead the 8mm potato did.
I made a table to show my readings on the experiment I observed. I
repeated the experiment three times for each potato diameter to make
the results more accurate. I then found the average result for each
potato cylinder. The diameter was measured in millimetres and the unit
of time we used was measured in minutes.
The results were not very good because the results from the graph did
not prove my prediction right. There were some points on the graph
that did nit fit on the curved line so I circled these points. The
experiment happened over a few days so that could have caused my
results to be read wrongly. I could improve this experiment by working
a lot quicker so that I can be sure that the potato cylinders are from
the same potato to make my results more accurate and to make it more
of a fair test.