Rates of Reaction and Equilibria

Question 1

What is Collision theory?

Answer 1

For a reaction to occur the particles must collide to have enough energy to collide successfully. Have energy greater than the activation energy.

Question 2

What is Activation energy?

Answer 2

is the minimum energy required for an experiment to occur.

Question 3

What is the role of a catalyst?

Answer 3

A catalyst speeds up a reaction by providing an alternate pathway with a lower activation energy so more of the collisions will be successful. Therefore there will be more successful per unit time.

Question 4

What happens if you increase the pressure/concentration:

Answer 4

More particles in a given volume,
So there will be a higher chance of particles colliding.
So there will be more sucessful collisions per unit time.

Question 5

What happens if you increase the surface area?

Answer 5

There is a larger area for particles to collide with.
So there will be a higher chance of particles colliding.
So there will be more sucessful collisions per unit time.

Question 6

What happens if you increase the temperature?

Answer 6

Increasing the temperature increases the kinetic energy of the particles so that they move faster.
So there will be more collisions per unit time.
More of the particles will have an energy higher than the activation energy so more collisions will be successful.
So there will be more successful collisions per unit time.

Question 7

What is Le Chantelier’s principle?

Answer 7

If a reaction at dynamic equilibrium is subjected to a change in conditions i.e. temperature concentration pressure then the equilibrium will shift to minimise this change.

Question 8

Concentration:

1. adding a substance ….
2. removing a substance …

Answer 8

1. means the equilibrium shift away from the substance added.
2. means the equilibrium shifts towards the substance removed.

Question 9

Temperature:

1. heat up
2. cool down

Answer 9

1. equilibrium shifts in the endothermic direction (+)

2. equilibrium shifts in the exothermic direction (-)

Question 10

Pressure (only gases):

1. increasing the pressure
2. decreasing the pressure

Answer 10

1. the equilibrium shifts to the side with the fewest gas molecules
2. the equilibrium shifts to the side with the most gas molecules.

Question 11

What do catalysts do?

Answer 11

speeds up the reaction without changing the position of equilbria. It speeds up the the forwards and backwards reactions equally.