Higher Chemistry SQs Collision Theory and Activation Energy

According to collision theory, a chemical reaction occurs when particles...

• Move randomly in all directions

• Have sufficient energy and collide with the correct orientation

• Are at room temperature

• Form a catalyst

What is meant by the term "activation energy"?

• The total energy of the products

• The energy lost in a reaction

• The minimum energy required for a reaction to occur

• The energy needed to break all bonds in the reactants

In a potential energy diagram, the activated complex is found at...

• The energy level of the products

• The energy level of the reactants

• The lowest point on the curve

• The peak of the energy barrier

A reaction occurs more quickly when the activation energy is lowered. What causes this to happen?

• Increase in temperature

• Use of a catalyst

• Increase in particle size

• Decrease in pressure

What is formed at the point of maximum energy during a reaction?

• Reactants

• Products

• Activated complex

• Catalyst

Why does increasing temperature increase reaction rate?

• It increases the concentration of products

• It lowers the activation energy

• It gives particles more energy to overcome activation energy

• It makes collisions less frequent

Which of the following statements about the activated complex is correct?

• It is more stable than the products

• It exists after the reaction has completed

• It is a short-lived, high-energy species

• It has lower energy than the reactants

What effect does increasing the concentration of reactants have on the rate of reaction?

• Decreases the activation energy

• Increases the number of successful collisions

• Increases the stability of the activated complex

• Reduces the energy of the products

The activation energy of a reaction is 60 kJ mol⁻¹. Which of the following changes would increase the number of particles with energy equal to or greater than this value?

• Decreasing pressure

• Lowering temperature

• Increasing temperature

In a reaction profile diagram, how is the activation energy represented?

• The energy difference between products and activated complex

• The energy difference between reactants and activated complex

• The energy released in the reaction

• The energy difference between reactants and products