Chapter 5.1 - Collision Theory

Question 1

State the factors that affect the rate of reaction:

Answer 1

Concentration 
Area
Catalyst 
Pressure 
Temperature

Question 2

How does increase in temperature affect rate of reaction ?

Answer 2

This increases the speed of particles, the particles take in the heat energy so they have extra energy which means more successive collisions

Average KE of particles increases
Increases heat energy,
Activation energy remains the same,
Particles have more KE energy so it helps reach activation energy faster

Question 3

How does increase in concentration affect rate of reaction ?

Answer 3

There are more particles present in a given volume so there are more chances of particles colliding

Question 4

How does increasing the pressure affect the rate of reaction ?

Answer 4

There are more particles in a given volume so more chance of successive collision

Question 5

How does increasing the surface area of a solid reactant affect the rate of reaction ?

Answer 5

The greater the surface area of a solid the more of its particles are available to collide with molecules.

Question 6

State what needs to happen for a collision to result in a reaction ?

Answer 6

The particles must have a certain energy enough to start breaking bonds

Question 7

State the meaning of the term rate of reaction (1)

Answer 7

Amount of substance used up per unit of time

Question 8

State the meaning of the term activation energy (1)

Answer 8

Minimum energy required for a reaction to occur

Question 9

In terms of collision theory explain why, at a fixed temperature, the rate of this reaction doubles when the concentration of the hydrochloric acid doubles. (2)

Answer 9

• twice the amount of HCL present/more number of acid particles/hydrogen ions
• twice the successful collision in a given time

Question 10

Explain what must happen for a reaction to occur between molecules of two different gases. (2)

Answer 10

Collisions with activation energy

Question 11

Explain why a small increase in temperature has a large effect on the initial rate of a reaction (2)

Answer 11

A small increase in temperature results in a greater number of successive collisions with sufficient energy

Question 12

Give one reason why most collisions between gas-phase reactants do not lead to a reaction. (1)

Answer 12

Particles do not have enough energy to collide

Question 13

Explain why, even in a fast reaction, a very small percentage of collisions leads to a reaction. (2)

Answer 13

• very few collisions have energy greater than the activation energy