The Concentration of Hydrogen Peroxide and Speed of The Rate at Which It is Broken Down by Catalase
To find out whether the concentration of Hydrogen Peroxide affects the
rate of decomposition of hydrogen peroxide when broken down by
Hydrogen peroxide is a liquid bi-product of many chemical reactions in
living things. It is toxic, so has to be broken down by the enzyme
catalase which is also found in most living things. E.g.
[IMAGE]Hydrogen peroxide catalase water + oxygen
2H2O2 (aq) 2H2 O + O2
The enzyme catalase (peroxidase) was the first enzyme discovered and
is one of the ...view middle of the document...
Enzymes work most efficiently at an optimum temperature and an optimum
[IMAGE]Rate of reaction a. without enzyme
[IMAGE][IMAGE][IMAGE]Volume of b. with enzyme
Time in minutes
NB rate of reaction is the actual number of substrate molecules
evolved per minute.
Volume of oxygen produced/evolved per minute is not in itself the rate
of reaction, but is indicative of the actual rate of reaction.
[IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE] H2 O
[IMAGE][IMAGE][IMAGE] H2 O2
10 vol H2 O2 20 vol H2 O2
Twice the concentration gives twice the number of hydrogen peroxide
molecules in the same volume; therefore twice the volume of oxygen
will be produced. This is because the frequency of collision will also
be doubled, as there are double the number of hydrogen peroxide
molecules for the catalase to collide with.
* Homogenise the potato in a pestle and mortar
* I will take 10ml of hydrogen peroxide and place it in a measuring
* To the measuring cylinder I will add 1.5g of homogenised potato,
which contains the enzyme catalase.
· I will then time it for 1 minute, and take a reading to see how much
oxygen foam has been produced; I will do this again after 2 minutes,
then after three minutes.
* I will do this 5 times in total, once with each concentration. The
concentrations are 2.5 vol, 5 vol, 10 vol, 20 vol, and 25 vol.
* I will then repeat the entire experiment.
I have chosen 2.5 as it is the lowest reasonable concentration that
will show a result. 5, 10 and 20 vol as they are twice the
concentration of the one before it and 25 as it is the highest
concentration that is safe to use. Above 25vol the hydrogen peroxide
becomes corrosive and the experiment would have to be performed under
close teacher supervision in a fume cupboard. This is not possible.
To make the experiment fair I will keep everything the same and only
vary the concentration of hydrogen peroxide. I have used doubling
concentrations in the hope of seeing a pattern in my results.
10 ml 2.5 vol hydrogen peroxide
10 ml 5 vol hydrogen peroxide
10 ml 10 vol hydrogen peroxide
10 ml 20 vol hydrogen peroxide
10 ml 25 vol hydrogen peroxide
5 measuring cylinders
5 weighing boats
1 pestle and mortar
Variables - In this investigation, the variables that affect the
activity of the enzyme, Catalase, were considered and controlled so
that they would...