Starter page 1:
Kinetics of the Harcourt Essen reaction
Find the order of reaction with respect to hydrogen peroxide, iodide and acid using a ‘clock’ reaction. 2)
To determine the rate equation, rate constant and the rate mechanism. 3)
To determine the order of reaction with respect to the catalyst. 4)
Look at the effect of a catalyst on the order of the reaction of hydrogen peroxide. 5)
Find the activation enthalpy of the reaction with a catalyst. 6)
Find the activation enthalpy of the reaction without a catalyst. There are many ways in which this experiment could be carried out. Hydrogen peroxide reacts with iodide ions in acid solution to form iodine. H2O2(aq) + 2H +(aq) + 2I–(aq) → I2(aq) + 2H2O(l) By varying the concentration of the iodide ion, you can determine the order of this reaction with respect to the concentration of the iodide ions. The liberated iodine is reacted with thiosulphate (VI) ions, which have been added to the reaction mixture. I2 + 2S2O32- → 2I- + S4O62-
When all of the thiosulphate ions have been used up, free iodine remains in solution and this is detected by the formation of a blue-black colour with starch indicator. The appearance of the blue-black colour represents the same extent of reaction in each case, and so the initial rate is proportional to 1/time.
Starter page 5:
Kinetics of the reaction between magnesium and acids
To explore the reaction of magnesium with hydrochloric acid, sulphuric acid, or nitric acid. 2)
Explore the effect of changing the concentration of the acid, the temperature or the addition of a catalyst on the rate of the reaction. 3)
First find the order of reaction with respect to acids, after which you must find the rate equation, the rate constant and the possible mechanism. 4)
Then find the activation enthalpy or explore the effect of added spectator ions. First of all, the rate equation must be determined using the inverted gas syringe method. Place excess acid...
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