Rates of Reaction and Equilibrium

Question 0

Define activation energy

Answer 0

The minimum energy required for a reaction to start

Question 1

Define rate of reaction

Answer 1

The change in concentration in a certain time

Question 2

How does a reactions happen?

Answer 2

Collisions between reactant particles
Must collide with more energy than the activation energy
Successful collisions

Question 3

How does a catalyst increase the rate of reaction?

Answer 3

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

Question 4

How does surface area increase the rate of reaction?

Answer 4

Increased surface area causes collisions to occur more frequently

Question 5

How does concentration in crease the rate of reaction?

Answer 5

More particles per unit of volume
Particles collide with a greater frequency
Higher frequency of successful collisions

Question 6

How does temperature increase the rate of reaction

Answer 6

Higher temperatures increase particle energy
Particles collide more frequently
More often with energy greater than the activation energy

Question 7

In relation to the Maxwell-Boltzmann,how does temperature increase the rate of reaction?

Answer 7

Significantly bigger proportion of particles have energy greater than the activation energy so the frequency of successful collisions increases

Question 8

What are the seven man features of theMaxwell-Boltzmann curve?

Answer 8

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

Question 9

How does a small increase in temperature affect the Maxwell-Boltzmann curve?

Answer 9

Emp shifts right
Peak gets lower
More molecules have required Ea
Same area under graph

Question 10

How does a large increase in temperatures affect the Maxwell-Boltzmann curve?

Answer 10

Emp shifts to the right
Peak is much lower and flatter
Many more molecules have required Ea

Question 11

How does an addition of a catalyst affect the Maxwell-Boltzmann curve?

Answer 11

Ea moves to the left

Many more molecules have required energy

Question 12

What happens to the curve if half the molecules are removed

Answer 12

The graph is half the height as the normal

Question 13

How will reducing the temperature affect the Maxwell-Boltzmann curve

Answer 13

It will increase the peak height and shift Emp left

Question 14

How will changing volume or adding an inert gas affect the Maxwell-Boltzmann Curve?

Answer 14

It does not affect it

Question 15

Define dynamic equilibrium

Answer 15

Forwards and backward reactions happening at the same rate
Concentration of reactants and products remains constant
Reaction should be closed to the surroundings

Question 16

Define le Chateliers principle

Answer 16

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.

Question 17

How does increasing the temperature affect equilibrium

Answer 17

Increase the rate
Shift to endothermic
If shift right, increase yield
If shift left, decrease yield

Question 18

How does decreasing the temperature affect equilibrium

Answer 18

Decreases rate
Shift to exothermic
If shift right, increases yield
If shift left, decreases yield

Question 19

How does changing the total pressure affect equilibrium

Answer 19

Shifts in the direction of fewer moles

Question 20

How does a change in concentration affect equilibrium

Answer 20

As concentration of reactant is increased, or concentration of products decreases, it shifts to the right

Vice versa

Question 21

Why is a high pressure a compromise?

Answer 21

Shifts to fewer moles - may mean a higher yield
Cost of producing and withstanding the high pressure
Cost of equipment

Question 22

How is temperature a compromise

Answer 22

Speeds up rate of reaction
May shift to left (endothermic reaction)
May decrease yield
Cost

Question 23

How does an iron catalyst affect equilibrium

Answer 23

Acts equally in forward and backward reactions, causing no shift in equilibrium
Increases rate of reaction