Rates of reaction - kinetics (A2)
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Hello, I'm investigating the rate of reaction between hydrogen peroxide and iodide ions. I have found the order of the reaction with respect to both reactants but the value of k is different when I calculate it by working out the gradient on each rate/concentration graph. I don't know what to do now, please help!! thank you
Ulex writes ...
Yes, the value of k will be different. The full rate equation is:
rate = k[H2O2]a x [I-]b x [H+]c
(where a, b and c are the orders of reaction with respect to each reactant.
When you determine a rate constant by the method you describe, you are not actually working out k itself; your value of 'k' from the hydrogen peroxide experiment includes factors for the concentrations of iodide ions and acid (which have certain constant values during this experiment). Your 'k' for this experiment is therefore actually k x [I-]b x [H+]c
Similar remarks apply to the value you get from the iodide experiments.
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updated: 17 April 2007
