Practical investigations
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Hello, for my individual investigation I am looking at the decomposition of hydrogen peroxide into H2O and O2 using an enzyme - catalase. I will investigate the reaction with varying temperatures and substrate/enzyme concentrations. I will folllow the reaction by measuring the volume of oxygen produced using an inverted burette.
For my second technique I was hoping to use titration, but I am confused about what I would put in the burette and what I would put in the conical flask. What indicator could I use to test the reaction had occurred? Thank you for your time.
Igloo writes ...
Your first method is fine.
As for your second approach, you could remove samples of the mixture at measured time intervals, using a pipette, and rapidly titrate with a standard acidified solution of potassium manganate(VII). No indicator is needed, since this purple-coloured reagent is self-indicating. It will go colourless on addition to the peroxide, then a pink/purple colour at the end-point.
This second approach is only going to work properly if the decomposition reaction is slow enough to enable you to carry out the titrations accurately. The removed samples should be immersed in an ice-bath to quench the decomposition reaction somewhat. You will need to research the reaction which occurs between hydrogen peroxide and manganate(VII) ions, and find out which acid is the best to use.
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Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
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updated: 26 March 2007
