Kinetics Quiz

This question is about the Maxwell–Boltzmann distribution of molecular energies in a sample of a gas shown in the following figure. What does the area under the curve represent?

• The total energy of the particles.

• The total number of particles.

• The number of particles that can react with each other.

• The total number of particles that have activation energy.

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.

Answer explanation

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

The question below is about the Maxwell–Boltzmann distribution shown for a sample of a gas, X, at two different temperatures. 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.

The apparatus in the figure below was set up to measure the time taken for 20.0 cm³ of sodium thiosulfate solution to react with 5.0 cm³ of hydrochloric acid in a 100 cm³ conical flask at 20 °C. The timer was started when the sodium thiosulfate solution was added to the acid in the flask. The timer was stopped when it was no longer possible to see the cross on the paper. What is likely to decrease the accuracy of the experiment?

• Rinsing the flask with acid before each new experiment.

• Stirring the solution throughout each experiment.

• Using the same piece of paper for each experiment.

• Using different measuring cylinders to measure the volumes of acid and sodium thiosulfate.

The previous experiment was repeated at 20 °C using a 250 cm³ conical flask. Which statement is correct about the time taken for the cross to disappear when using the larger conical flask?

• The time taken will not be affected by using the larger conical flask.

• The time taken will be decreased by using the larger conical flask.

• The time taken will be increased by using the larger conical flask.

• It is impossible to predict how the time taken will be affected by using the larger conical flask.

The graph above 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 E_A to the right.

• The area under the curve to the right of E_A 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.

This question is about the Maxwell–Boltzmann distribution of molecular energies in a sample of a gas shown in the figure above. Which letter best represents the mean energy of the molecules?

• A

• B

• C

• D

The total area under the distribution curve represents

• total energy.

• activation energy.

• total number of reacting molecules.

• total number of molecules present.

The question below is about the Maxwell–Boltzmann distribution shown for a sample of a gas, X, at two different temperatures. Which letter shows the mean energy of the molecules at the higher temperature?

• P

• Q

• R

• S

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