Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: plles on March 05, 2017, 05:36:46 AM
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Hi everyone! For a school project, I am conducting an experiment investigating the relationship between rate constant and temperature . The reaction I'm using is the iodine clock reaction, hydrogen peroxide variation.
The problem is that seconds after the starch and iodine complex and create a dark solution, a dark pink gas forms. I presumed this is iodine gas so I am now conducting the experiment in a ventilated area of the lab to avoid any irritations but I don't understand why the gas even forms in the first place, especially because the gas forms already at room temperature and its boiling point is about 183°C. Could it be that the concentrations of my reactants are too high? I only calculated them to be in the required ratio so that the thiosulphate is limiting, but I had not considered that perhaps they are too high.. although most solutions are either 0.01 or 0.02 M. Any help as to why the gas is forming is greatly appreciated!
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Besides concentrations, I think you may used glass that contained some amount of compound which catalytically decomposed hydrogen peroxide and evolved oxygen took some iodine analogously to steam distillation.