Determination of the order of a reaction

O

Owen.A

Just had a look at the link from experiments on film (wales) for the order of reaction practical, seems similar to the Iodine clock one.
Ive tried it using the items listed but as soon as I add H2SO4 1.0M it starts to turn brown without getting to adding peroxide. All the chemicals are freshly made, am I right in thinking the concentration is too high for this one?

16. Determination of the order of a reaction

Determination of the order of a reaction.
experiments.science.cymru experiments.science.cymru
 
M

Medchemist

Sulfuric acid is and oxidising agent only in high concentration and I'm going to assume your bench acids are correctly made.

The most likely culprit is oxygen dissolved in solution, if the water you use sits around for a while it will absorb atmospheric oxygen which will in turn start oxidising the acidified KI before you get to add the H2O2.

Try remaking the solutions with freshly boiled distilled/deionised water and keeping then in tightly screwed on bottles (i.e. not the polystop bottles which allow gasses to diffuse in/out)
 
W

WMC_Ste

Also make sure you are not mixing up Iodide with Iodate, that happens a few times. If you Iodide and iodate has been mixed together it can release Iodine when introduced to sulphuric acid.
 
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