Rates of Reaction and Equilibrium Flashcards
Define activation energy
The minimum energy required for a reaction to start
Define rate of reaction
The change in concentration in a certain time
How does a reactions happen?
Collisions between reactant particles
Must collide with more energy than the activation energy
Successful collisions
How does a catalyst increase the rate of reaction?
Speeds up the rate of reaction without being used up itself
Lowers the activation energy
Provides an alternative pathway/route
More particles will have an energy that is higher than activation energy
How does surface area increase the rate of reaction?
Increased surface area causes collisions to occur more frequently
How does concentration in crease the rate of reaction?
More particles per unit of volume
Particles collide with a greater frequency
Higher frequency of successful collisions
How does temperature increase the rate of reaction
Higher temperatures increase particle energy
Particles collide more frequently
More often with energy greater than the activation energy
In relation to the Maxwell-Boltzmann,how does temperature increase the rate of reaction?
Significantly bigger proportion of particles have energy greater than the activation energy so the frequency of successful collisions increases
What are the seven man features of theMaxwell-Boltzmann curve?
Goes through 0,0 as no molecule has no energy
Area under graph is he total number of particles
Only molecules in the shaded area (less than Ea) collide with enough energy to react
Never meet the x axis
There is an Ea - activation energy
Emp - most probable value
Mean energy - to the right of Emp
How does a small increase in temperature affect the Maxwell-Boltzmann curve?
Emp shifts right
Peak gets lower
More molecules have required Ea
Same area under graph
How does a large increase in temperatures affect the Maxwell-Boltzmann curve?
Emp shifts to the right
Peak is much lower and flatter
Many more molecules have required Ea
How does an addition of a catalyst affect the Maxwell-Boltzmann curve?
Ea moves to the left
Many more molecules have required energy
What happens to the curve if half the molecules are removed
The graph is half the height as the normal
How will reducing the temperature affect the Maxwell-Boltzmann curve
It will increase the peak height and shift Emp left
How will changing volume or adding an inert gas affect the Maxwell-Boltzmann Curve?
It does not affect it
Define dynamic equilibrium
Forwards and backward reactions happening at the same rate
Concentration of reactants and products remains constant
Reaction should be closed to the surroundings
Define le Chateliers principle
If the conditions of a system initially at equilibrium are changed, the equilibrium will shift such in a direction as to tend to restore the original conditions, opposing the changes.
How does increasing the temperature affect equilibrium
Increase the rate
Shift to endothermic
If shift right, increase yield
If shift left, decrease yield
How does decreasing the temperature affect equilibrium
Decreases rate
Shift to exothermic
If shift right, increases yield
If shift left, decreases yield
How does changing the total pressure affect equilibrium
Shifts in the direction of fewer moles
How does a change in concentration affect equilibrium
As concentration of reactant is increased, or concentration of products decreases, it shifts to the right
Vice versa
Why is a high pressure a compromise?
Shifts to fewer moles - may mean a higher yield
Cost of producing and withstanding the high pressure
Cost of equipment
How is temperature a compromise
Speeds up rate of reaction
May shift to left (endothermic reaction)
May decrease yield
Cost
How does an iron catalyst affect equilibrium
Acts equally in forward and backward reactions, causing no shift in equilibrium
Increases rate of reaction
