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Luminol - HSN forum

# Luminol

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### #1Jammie1000000

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Posted 19 November 2007 - 12:31 PM

I am doing an investigation on luminol and how the concentrations/temperature affects the length of time the glow lasts for but my teacher says that it isnt complex enough to gain me the marks. Any ideas how to make it up to advanced higher level. He says that i should possibly look at kinetics. :S

### #2Tux78

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Posted 30 January 2008 - 06:58 PM

Draw a graph of Concentration against time and then differentiate to find the Gradient of the tangent. this will give you the rate of reaction at a particular concentration. Repeat for double the concentration to determine the order of the reaction. Look at the topic on scholar to get some ideas. Its working out the rate of reaction that you need for kinetics. Not sure if that is exactly what you mean but hope it helps in someways.

### #3Marcus

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Posted 30 January 2008 - 10:32 PM

QUOTE(Tux78 @ Jan 30 2008, 06:58 PM)
Draw a graph of Concentration against time and then differentiate to find the Gradient of the tangent. this will give you the rate of reaction at a particular concentration. Repeat for double the concentration to determine the order of the reaction. Look at the topic on scholar to get some ideas. Its working out the rate of reaction that you need for kinetics. Not sure if that is exactly what you mean but hope it helps in someways.

this would work, but how will you calculate the concentration at particular times, AFAIK luminol isn't an acid/alkali (but i could be wrong) so pH is out of the question. A sightly more feasible method would be to pick a constant point in the reaction (eg, when the glow falls to a certain brightness), time how long it took to reach that, then take the reciprocal of time(). This would only worked if the end point was the same for all concentrations.
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### #4Jammie1000000

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Posted 10 March 2008 - 09:08 AM

That is what i haev done so far but my chemistry teacher said that it was inaccurate and not to advanced higher level.

### #5Marcus

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Posted 11 March 2008 - 08:04 PM

QUOTE(Jammie1000000 @ Mar 10 2008, 09:08 AM)
That is what i haev done so far but my chemistry teacher said that it was inaccurate and not to advanced higher level.

But isn't the whole concept of kinetics advanced higher?
I looked into the reaction. It seems the reaction involves OH- ions? This means as reaction progresses pH will fall. You can maybe measure rate of reaction using change in pH?

This website seems to provide some very good background for this reaction, including a very...erm...interesting method of determining rate; you should suggest it to your teacher lol
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