Determining the Activation Energy of the Reaction Between Bromide Ion and Bromate Ion in Acid Solution
By reacting Potassium Bromide and Potassium Bromate in the acid
solution in varies temperature, we can then determine the Activation
Energy of the reaction in different temperature through the equation:[IMAGE].
So it is not advisable to perform the
experiment at high temperatures as the time of reaction is too short,
it is not easy for us to record.
4. Why is it not necessary to know how far the reaction has proceeded
at the point where the methyl red is decolourized?
In the experiment, the number of mole and the molarity of each
chemicals used are the same. And the appearance of the pink colour
only determines that there are some content of the reaction has
processed. As the result, it is only necessary for us to compare the
time required for the reaction mixture to reach the point the
decolourization occurs at different temperature.
5. The Arrhenius equation can be represented as: [IMAGE]
(a) Can [IMAGE] substitute k in this equation? Why?
[IMAGE] can substitute k in this equation. As in the above experiment,
the initial rate can be represented by [IMAGE] due to the constant
concentration of the reactants. Also the rate constant k is
proportional to the rate of the reaction when the temperature changes.
Therefore, [IMAGE] can substitute k.
(b) Derive an equation relating ln k and 1/T.
ln k = ln A Â– Ea/RT
ln k = ln A Â– (Ea/R)(1/T)
(c) Determine Ea by plotting a suitable graph. (Given R=8.3JK-1 mol-1
âˆµ lnk = lnA Â– Ea/RT
=68904.6 J mol-1
=68.9046 kJ mol-1
6. Explain why the reaction rate can be affected by temperature.
As the temperature increase, the numbers of vibration increase, the
speed of the particles increase, then the frequency of collision
increases. As the result, the frequency of effective collision also
increases. Therefore the reaction rate will increase vice versa.