Chemical Reaction Kinetics

Which of the following best describes chemical kinetics?

• The study of the speed at which chemical reactions occur

• The study of the equilibrium position of chemical reactions

• The study of the energy changes during a chemical reaction

• The study of the chemical composition of substances

Which of the following reactions is a first-order reaction?

• A → Products

  (Rate = k[A]²)
  
  
  
  

• A → Products

  (Rate = k[A])
  
  

• A + B → Products

  (Rate = k[A][B])

• A + B → Products

  (Rate = k[A]¹[B]²)

Which of the following variables does NOT affect the rate of a chemical reaction?

• Concentration of reactants

• Temperature
  
  

• Presence of a catalyst

• Color of the reactants

Increasing the temperature generally increases the rate of a reaction because:

• It increases the activation energy

• It decreases the frequency of collisions between molecules

• It increases the Kinetic energy and frequency of collisions between molecules

• It decreases the kinetic energy of the molecules

The reaction rate is defined as

• The time taken for the reactants to be consumed completely

• The change in concentration of a reactant or product per unit time

• The equilibrium constant of the reaction

• The energy released during the reaction

Answer explanation

Reaction rate measures how quickly reactants are converted into products, typically expressed as the change in concentration over time

16. Activation energy is:

• The energy required to initiate a reaction

• The total energy released by a reaction

• The energy difference between reactants and products

• The average kinetic energy of molecules

Which unit is typically used for the rate constant (k) in a first-order reaction?

• Molarity per second (M/s)

• Per second (s⁻¹)

• Molarity per minute (M/min)

• Per molarity per second (M⁻¹s⁻¹)

Answer explanation

For a zero-order reaction, the rate of reaction:

• Is independent of the concentration of reactants

• Depends linearly on the concentration of reactants

• Depends on the square of the concentration of reactants

• Is inversely proportional to the concentration of reactants

Answer explanation

For Zero Order Reaction

r_A =k[A]⁰

No concentration terms are present in the rate expression

1. In the rate equation r=k[A]ⁿ , what does the exponent n represent?

• Rate constant

• Order of reaction

• Temperature

• Activation energy

3. How is the order of a reaction determined?

• Experimentally

• From the molecularity

• By the stoichiometry of the reaction

• Using the Arrhenius equation