September 20, 2021, 10:02:13 AM
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Topic: Luminol experiment gone wrong?  (Read 313 times)

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Offline struggling_kemist

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Luminol experiment gone wrong?
« on: June 15, 2021, 08:56:16 AM »
So here's what i posted in the past about my experiment https://www.reddit.com/r/forensics/comments/nefrm7/doing_a_lab_experiment_using_luminol/

But when i conducted the practical today the luminol solution turned black after mixing with chlorax bleach (I only have household bleach available), the solution then turned green which I suspected wasn't the product of a reaction, but rather the colour obtained after the two solutions mixed.

Here's how I made my luminol solution:

30ml of 0.2M of copper sulphate as catalyst (changing this concentration as independent variable)

0.1g of luminol

sodium hydroxide + ammonia solution

11g of sodium bicarbonate

all added together to make a 250 ml solution and 50ml is used in each trial to add to the 50ml of diluted bleach solution.

I was unable to fully dissolve the luminol even thought I've tried to increase the pH of the solution. One possible problem with the experiment not working might be that I added too much sodium hydroxide (to a point that the luminol solution turned from light green to bluish green).

Pls give me some advice! Wud appreciate any input, thanks in advance!

Online Babcock_Hall

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Re: Luminol experiment gone wrong?
« Reply #1 on: June 15, 2021, 09:47:44 AM »
Are you following a literature protocol?  Do I understand correctly that hydrogen peroxide is also present?  You may find this paper helpful:  Barni F et al., Talanta 72 (2007) 896–913.  doi:10.1016/j.talanta.2006.12.045
« Last Edit: June 15, 2021, 10:15:53 AM by Babcock_Hall »

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