Chapter 10

Question 1

What changes rate of reaction ?

Answer 1

• temperature
• concentration of reactants
• catalyst
• pressure (gasses)
• the surface area

Question 2

What is needed for a successful reaction ?

Answer 2

• they need sufficient activation energy
• correct orientation of the molecules
• particles need to collide

Question 3

What is the effect of increasing concentration on rate of reaction

Answer 3

• increasing concentration leads to more reacting particles in a given volume
• this means the particles are more crowded and there will be a higher frequency of collisions
• if the required activation energy is there is an increase in the rate of successful collusions
• therfore a greater average rate of reaction

Question 4

What are the 2 types of catalysts ?

Question 5

What are the benefits of using a catalyst ?

Answer 5

• activation energy lowered, meaning less energy is needed for the reaction
• lower temperatures can be used, saving money as well as resources
• therefore more profit and less harmful effects of energy generation

Question 6

What does a Boltzmann distribution graph look like ?

Answer 6

Question 7

What does a Boltzmann distribution graph look like ?

Answer 7

• In the model we assume that all collisions between particles and the surface of the container are elastic (no loss in kinetic energy)
• the total area under the graph stays the same

Question 8

What happens to boltzmann distribution curve after an increase in temperature ?

Answer 8

• the peak flattens and shifts to the right

Question 9

What does an equilibrium graph look like ?

Answer 9

Question 10

What is dynamic equilibrium?

Answer 10

• closed system
• the rate of the forward reaction = the rate of the backwards reaction
• concentration of reactants and products stay the same

Question 11

What is Le Chatelier’s principle ?

Answer 11

when a change is made to a reaction of equilibrium, the position of equilibrium moves to oppose the original change ?

Question 12

What happens when you change the concentration of the system ?

Answer 12

If concentration of reactants increases - the equilibrium position move away from the reactants, therefore shifts to the right, to increase the concentration of products and favour the forwards reaction.

If concentration of reactants decrease - the equilibrium position shifts to the left to favour the backwards reaction to increase the concentration of reactants.

Question 13

What happens if you change the temperature of the system ?

Answer 13

Increase in temperature - more energy in the system favours the endothermic reaction to reverse the change, shift to the right

Decrease in temperature - less energy in the system favours the exothermic reaction to reverse the change, shift to the left

Question 14

What happens when you change the pressure of a system ?

Answer 14

If the pressure is increased - favours the reaction with less moles of gas to decrease the pressure again
If pressure is decreased - favours the reaction with more of gas to increase the pressure

E.g N2 + 3H2 -> 2NH3, to increase the production of ammonia increase pressure to favour forwards reaction