Rate and Extent of Chemical Change Flashcards
How and why does surface area affect the rate of reaction?
Only the surface particles of a substance can react, so increasing the surface area increases the number of particles that are available to react. This increases the frequency of successful collisions
How and why does temperature affect the rate of reaction?
Increased temperatures mean particles can move around more quickly. This means more particles meet the activation energy and the frequency of successful collisions increases
How and why does concentration affect the rate of reaction?
Increased concentration means there are more particles in the same volume, so more particles per unit volume. This means the frequency of successful collisions increases
How and why does pressure affect the rate of reaction?
Increasing the pressure means there are the same amount of particles in a smaller volume, so more particles per unit volume. This means the frequency of successful collisions increases.
How and why do catalysts affect the rate of reaction?
Catalysts reduce the activation energy required for the reaction to take place by providing an alternate pathway. This means more particles meet the required activation energy and the frequency of successful collisions increases.
How do you calculate the mean rate of reaction?
Reactants used / Time
Products formed / Time
What is activiation energy?
The minimum energy particles must have in order to react
What is Le Chatelier’s Principle?
Whenever a change in conditions is introduced to a system at equilibrium, the position of equilibrium shifts to counteract the change
How does increasing the concentration of reactants affect the yield of a reaction?
The position of equilibrium shifts to counteract the change, to the right
This will favour the forward reaction
The yield will increase
How does increasing the pressure affect the yield of a reaction?
The position of equilibrium will shift to counteract the change
The reactants take up less space than the product
The position of equilibrium shifts to the left
This will favour the backwards reaction
The yield will decrease
How does increasing the temperature affect the yield of a reaction?
The position of equilibrium will shift to counteract the change
The endothermic reaction will decrease in temperature
The position of equilibrium will move to the left
This will favour the backwards reaction
The yield will decrease
How does a catalyst affect the yield of a reaction?
Position of equilibrium remains the same
Catalyst speeds up both reactions
No effect on yield
What is the word equation for the Haber Process?
Nitrogen + Hydrogen –> Ammonia
What are the conditions required for the Haber Process?
Passed over an iron catalyst
450°C and 200 atmospheres pressure
Remaining H and N are recycled
look at book 1
