Year 13 How Fast? Part 2

To determine the activation energy (E_a) for a reaction, the variation of reaction rate with temperature is investigated.

The rate constant, k, for the reaction is related to the absolute temperature, T, by the Arrhenius equation.

The activation energy for the reaction could be found by plotting a graph of

• A

• B

• C

• D

In the industrial process involving gas phase reactions to produce ammonia, many collisions between molecules are unsuccessful because

• gas phase reactions are reversible.

• the collisions are not energetic enough to break the bonds in the molecules.

• gas phase reactions can only occur when a catalyst is present.

• gas phase reactions can only occur when UV light is present.

This question is about how catalysts work.

Gaseous reactants attach to the catalytic surface by the process of

• absorption

• activation

• adsorption

• desorption

From the four sketch graphs, which could be a graph of rate of reaction, on the vertical axis, against the concentration of a reactant for a zero order reaction?

• A

• B

• C

• D

From the four sketch graphs, which could be a graph of rate of reaction, on the vertical axis, against the square of the concentration of a reactant for a second order reaction?

• A

• B

• C

• D

From the four sketch graphs, which could be a graph of the concentration of a reactant, on the vertical axis, against time for a first order reaction?

• A

• B

• C

• D

From the four sketch graphs, which could be a graph of ln k, on the vertical axis, against reciprocal of temperature, 1/T, for a reaction?

• A

• B

• C

• D

The energy marked X in the Maxwell-Boltzmann distribution shows

• the most common energy of the molecules.

• the activation energy of the reaction.

• the activation energy of a catalysed reaction.

• the number of molecules with energy greater than the activation energy.

Consider the Maxwell-Boltzmann distribution of energies for a gas shown below. E_a represents the activation energy.

The shaded area of the diagram indicates the total number of particles that

• do have enough energy to react.

• do not have enough energy to react.

• do have enough energy to react in the presence of a catalyst.

• do not have enough energy to react in the presence of a catalyst.

This question is about the oxidation of ammonia.

The diagram shows a Maxwell-Boltzmann distribution of particle energies, including the activation energy, E_a , for a reaction.

An increase in temperature will

• increase the area under the curve.

• move the peak of the curve to the right.

• raise the height of the peak.

• move the position of the activation energy, E_a , to the left.