[Maximum number: 1]

The Boltzmann distribution for a gas at constant temperature is shown below.

If the temperature of the gas is reduced by $10^{\circ} \mathrm{C}$ the graph changes shape.
What happens to the values of n for the molecular energies X, Y and Z ?

higher

lower

higher

lower

higher

lower

[Maximum number: 1]

The diagram represents, for a given temperature, the Boltzmann distribution of the kinetic energies of the molecules in a mixture of two gases that react together. The activation energy for the reaction, $E_{\mathrm{a}}$ , is marked.

The dotted curves below show the Boltzmann distribution for the same reaction at a higher temperature. On these diagrams, H represents the activation energy at the higher temperature.

Which diagram is correct?

[Maximum number: 1]

The diagram shows the Boltzmann distribution of energies in 1 mole of a gas. The gas can take part in a reaction with an activation energy, $E_{a}$ .

Which statement correctly describes the effect of an increase in temperature?

Peak P will be higher and fewer molecules will have energy $>E_{\mathrm{a}}$ .

Peak P will be higher and more molecules will have energy $>E_{\mathrm{a}}$ .

Peak P will be lower and fewer molecules will have energy $>E_{\mathrm{a}}$ .

Peak P will be lower and more molecules will have energy $>E_{\mathrm{a}}$ .

[Maximum number: 1]

The diagram shows the Boltzmann energy distribution curve for molecules of a mixture of two gases at a given temperature. For a reaction to occur the molecules must collide together with sufficient energy.

$E_{\mathrm{a}}$ is used to represent the activation energy for the reaction between the gases. Of the two values shown, one is the activation energy for a catalysed reaction, the other for an uncatalysed reaction.

Which statement about $E_{a 1}$ is correct?

$E_{a 1}$ corresponds to a catalysed reaction with fewer effective collisions than the uncatalysed reaction.

$E_{a 1}$ corresponds to an uncatalysed reaction with fewer effective collisions than the catalysed reaction.

$E_{a 1}$ corresponds to a catalysed reaction with a greater number of effective collisions than the uncatalysed reaction.

$E_{a 1}$ corresponds to an uncatalysed reaction with a greater number of effective collisions than the catalysed reaction.

[Maximum number: 1]

The Boltzmann distribution is shown for a sample of gas at an initial temperature, $T_{1}$ .

The sample of gas was heated to temperature, $T_{2}$ .
What is the correct distribution for the higher temperature, $T_{2}$ ?

[Maximum number: 1]

The Boltzmann distribution of molecular energies in a sample of aqueous hydrogen peroxide at room temperature is shown.

Which diagram shows the Boltzmann distribution of molecular energies of aqueous hydrogen peroxide maintained at room temperature when a catalyst, manganese(IV) oxide, is added?

[Maximum number: 1]

The diagram below represents, for a given temperature, the Boltzmann distribution of the kinetic energy of the molecules in a mixture of two gases that react slowly together.

The activation energy for the reaction, $E_{\mathrm{a}}$ , is marked.
When the reaction is catalysed, the rate of reaction increases a little.
What will be the position of $E_{\mathrm{a}}$ for the catalysed reaction?

[Maximum number: 1]

The diagram shows a Boltzmann distribution of the energies of gaseous molecules and the activation energies, $E_{\mathrm{a}}$ , of a reaction with and without a catalyst.

Which statement about this distribution curve is correct?

If the temperature of the gas is increased, the maximum of the curve becomes higher.

If the temperature of the gas is increased, the maximum of the curve moves to the left.

The fraction of molecules that react in the presence of a catalyst is shown by

The fraction of molecules that react in the absence of a catalyst is shown by N

[Maximum number: 1]

The diagram shows the Boltzmann distribution of energies in a gas. The gas undergoes a reaction with an activation energy, $E_{a}$ . The peak of the distribution is labelled P.

If the same reaction is carried out in the presence of a catalyst, which statement is correct?

The peak P is at a lower height and the position of $E_{\mathrm{a}}$ moves to the left.

The peak P is at a lower height and the position of $E_{\mathrm{a}}$ moves to the right.

The peak P remains at the same height and the position of $E_{\mathrm{a}}$ moves to the left.

The peak P remains at the same height and the position of $E_{\mathrm{a}}$ moves to the right.

[Maximum number: 1]

The molecular energy distribution curve represents the variation in energy of the molecules of a gas at room temperature.

Which curve applies for the same gas at a lower temperature?