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Asked by x.nic.x | Sep 5, 2008 | A Level > Biology > Coursework
x.nic.x asks:

For my A2 coursework I'm looking at the effects of inhibitors on catalase activity in potato and liver. I wanted to use ethanol as the inhibitor, but I found something on the internet that said hydrogen peroxide and ethanol together could cause some sort of spontaneous combustion. Is it safe to use ethanol for this?

Also, what concentration of hydrogen peroxide would you suggest using? And how much hydrogen peroxide, ethanol and liver/potato should be used in order to get results?

Thanks in advance.

etutor answers:

Hydrogen peroxide decomposes into water and oxygen and the oxygen makes the ethanol more vigorously combustible. Normally, ethanol burns fairly calmly, but with added oxygen, in can cause an explosion. That said, you will not be using pure ethanol or highly concentrated hydrogen peroxide, not large quaktities of either, so I don't think it should be a problem, although you should certainly keep the experiment away from naked flames. It will certianly be something concrete to put in your risk assessment! I would consult your teacher, and, if he/she is not sure, he/she could ring an organisation called CLEAPSE (all schools belong to it and teachers know about it) to get more qualified advice than I can give.

Normal hydrogen peroxide in schools is '20 volume' (concentrations of hydrogen peroxide tend to be given in 'volumes'). This is normally used in experiments but it could be diluted and it would still work. I can't really advise about amounts and concentrations because all of these factors interact - you really need to do a preliminary experiment to find optimums. Bear in mind that liver tends to 'work' much faster than potato.

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