Chemical Kinetics

Which statement best defines rate of reaction?

• The time taken for the reaction to reach completion.

• The speed at which the reaction occurs.

• The change in concentration of a reactant or product over time.

• The increase in concentration of a reactant or product over time.

Which of the following could be used to follow the rate of a reaction?

I. Change in temperature as the reaction proceeds

II. Change in colour as the reaction proceeds

III. Change in electrical conductivity as the reaction proceeds

• I and II only

• I and IIl only

• Il and IIl only

• I ,ll and IIl only

A student wished to follow the rate of the reaction between calcium carbonate and hydrochloric acid. Which of the following methods would not work?

• Measuring the volume of carbon dioxide gas evolved over time.

• Measuring the change in mass of the contents of the flask over time.

• Measuring the change in colour of the contents of the flask over time.

• Measuring the change in pH of the contents of the flask over time.

For two particles to react when they collide what must be true according to collision theory?

• They must both have the same kinetic energy.

• All their chemical bonds must be broken.

• They must collide with the correct geometry or orientation.

• They must be in the gaseous or liquid state.

Which of the following factors affect the rate of a reaction according to collision theory?

I. The frequency of the collisions between reactant particles.

II. The orientation of the particles when they collide.

III. The number of reactant particles with E greater than or equal to Ea.

• I and II only

• I and III only

• II and III only

• l,II and III only

Which explains why increasing the temperature increases the rate of a chemical reaction?

• More reactant particles possess energy greater than or equal to the activation energy.

• The activation energy decreases at higher temperatures.

• Reactant particles travel faster at higher temperatures.

• Reactant particles are more likely to be in the gaseous state at higher temperatures.

Which will not generally increase the rate of a chemical reaction?

• Increasing the surface area of solid reactant particles.

• Increasing the size of solid reactant particles.

• Increasing the concentration of the reactant particles.

• Decreasing the activation energy.

Which is a correct statement about the rate of a chemical reaction?

• It can only be determined experimentally.

• It can be deduced from the chemical equation for the reaction.

• It can be predicted from the sign and value of the enthalpy change, ∆H, for the reaction.

• It only depends on the nature of the reactants not on their concentration.

Which is a true statement about two Maxwell-Boltzman energy distribution curves

drawn for a fixed amount of gas at two different temperatures, T K and (T+10) K?

• Both curves will peak at the same height.

• The area under both curves will be the same.

• Both curves will have the same number of particles with higher energy.

• he average energy for both curves will be the same.

A reaction between an acid and a metal carbonate takes 60 seconds before it is

completed. Why is the initial rate of the reaction faster than the rate after 50 seconds?

• The concentration of the acid decreases during the reaction.

• The temperature of the reaction decreases as it proceeds.

• the particle size of the metal carbonate decreases as the reaction proceeds.

• The carbon dioxide produced dissolves in the water as the reaction proceeds.