Kinetics AS

The figure shows a typical energy distribution for particles of an ideal gas in a sealed container at a fixed temperature. Which of the following statements is true?

• Position A represents the mean energy of a molecule in the

  container.

• Addition of a catalyst moves the position of EA to the right.

• The area under the curve to the right of EA represents the

  number of molecules with enough energy to react.

• The position of the peak of the curve at a higher temperature

  is further away from both axes.

The Maxwell–Boltzmann distribution of molecular energies in a sample of gas at a fixed temperature is shown.

Which letter represents the mean energy of the molecules?

• A

• B

• C

• D

Which statement is correct for the distribution curve of molecular energies in a gas?

• The curve is symmetrical about the maximum.

• There are always some molecules with zero energy.

• The position of the maximum of the curve is not dependent on the temperature.

• The mean energy of the molecules is greater than the most probable energy of the molecules.

The diagram shows the Maxwell−Boltzmann distribution of molecular energies in a gas at two different temperatures. Which letter represents the most probable energy of the molecules at the higher temperature?

• A

• B

• C

• D

Line X in Figure 8 represents the volume (V) of gas formed with time (t) in a reaction between an excess of magnesium and aqueous sulfuric acid.

Which line represents the volume of hydrogen formed, at the same temperature and pressure, when the concentration of sulfuric acid has been halved?

• 
• 
• 
• 

Which letter shows the mean energy of the molecules at the higher temperature?

• P

• Q

• R

• S

Which statement is correct for the higher temperature?

• The area under the curve to the left of E_a decreases.

• The total area under the curve increases.

• The activation energy decreases.

• More molecules have the mean energy.