Question

Is each of the following statement true? If not explain.

a) At a given temperature, all molecules have the same kinetic energy

b) The higher the activation energy of the reaction is, the lower the reaction rate

c) A temperature increase by 10

Answer 1

a) false: At least for a classical ideal gas, the distribution of kinetic energy at temperature T corresponds to the Maxwell-Boltzmann distribution at that temperature.
This expression simply means that, while high energy particles are possible, they are not probable, with their probability decaying exponentially as a function of their energy ratio with kT. Hence, the expected energy of a randomly chosen particle is on the order of kT.

b) true: because there are more particles that are reacting, if you had a higher activation energy less particles would reach the right conditions at a given time and then you would have a slower reaction.

c) true

d) false: No, reactants only turns into products if the reactant molecules have a energy greater than the activation energy. The activation energy is the minimum amount of energy needed for a reaction to occur

e) false: it would decrease as less original reactants were left

f) Because the activation energy is reduced more collisions have enough energy to react and SO the frequency of successful reactions is increased.
g) So in fact the rate of the reaction will depend on the height of the activation energy (that peak you see in the potential energy diagrams for reactions). It doesn't matter where the level of the products is, only the height of the peak.

h) The overall enthalpy change in a common reaction would not change. Only the path to get there would change. A catalyst basically lessens the activation energy required to get the reaction to take place.