Unit 5: Topic 5 - Collision Model

Question 1

What are the requirements for a reaction to occur?

Answer 1

Molecules must collide with each other in order for reactions to occur. However, they need to collide with enough energy (activation energy) and proper orientation.

Question 2

What are the requirements for a reaction to occur? (Cont.)

Answer 2

Collisions between reactants need to have a certain amount of energy (activation energy) and proper orientation for products to be produced.

Activation energy: The amount of energy required in a collision to cause a reaction. (This doesn’t change with temp)
If the molecules have higher activation energy, the reaction rate will be slower because fewer molecules are able to overcome the activation energy.
Orientation: The molecules have to be at a certain angle so that new bonds can be formed.

Question 3

What other factor increases reaction rate and how is this evident in the Maxwell-Boltzmann curve?

Answer 3

The reaction rate should increase with increasing temperature.
1. At higher temp, the particles move faster resulting in more collisions.
2. There will be more collisions with the required activation energy because higher temp = more kinetic energy.

The Maxwell-Boltzmann curve also shows this idea. The dotted line is the activation energy. The area under the red line has a greater area than that of the blue line. This means more molecules at the higher temp have the required activation energy and thus is able to make more successful collisions.

Question 4

Which of the following best helps explain why an increase in temperature increases the rate of a chemical reaction?
A. At higher temperatures, reactions have a lower activation energy
B. At higher temperatures, reactions have a higher activation energy
C. At higher temperatures, every collision results in the formation of a product.
D. At higher temperatures, high-energy collisions happen more frequently.

Answer 4

The answer is D. A and B aren’t correct because temperature DOESN’T change the activation energy of a molecule. C isn’t correct because more collisions would be successful but not ALL. D is correct since higher temp means more high-energy collisions.