Rate Of Reaction

Question 1

How to work out rate of reaction

Answer 1

Amount of reactant or product used / time

Question 2

Factors which affect rate

Answer 2

• concentration
• pressure
• temperature
• SA
• catalyst

Question 3

Collision theory

Answer 3

states that chemical reactions occur only when the reactant particles collide with sufficient energy to react

Question 4

Affects of increasing pressure, concentration and SA

Answer 4

Increases frequency of successful collisions and so increases rate

Question 5

Affects of increasing temperature on rate

Answer 5

Means particles have more energy (kinetic) when they collide so the frequency of successful collisions increases

• increases the frequency of successful collisions and makes the collisions more energetic so increases rate of reaction

-> makes line steeper on a graph but doesn’t increase quantity of product

Question 6

Catalysts

Answer 6

• substances that speed up chemical reactions without being used up
• work by providing an alternate pathway of lower activation energy

Question 7

What is Dynamic Equilibrium

Answer 7

When the forward and backwards reactions are occurring at the same time and at the same rate

Question 8

Effects of changing conditions on equilibrium

Answer 8

If a system is at equilibrium and a change is made then the system responds by counteracting the change (Le Chateliers principle)

Question 9

The effect of changing concentration

Answer 9

If concentration of reactants is increased:
- equilibrium shifts to the right so more product is produced and yield increases

If concentration of products is increased:
- equilibrium shifts to the left so more reactant is produced and yield decreases

Question 10

The effect of temperature changes on equilibrium

Answer 10

If temperature is increased:
- equilibrium moves in the direction of the endothermic reaction

If temperature is decreased:
- equilibrium moves in the direction of the exothermic reaction

Question 11

The effect of pressure changes on equilibrium

Answer 11

If pressure increases:
- equilibrium shifts to the side with the fewest moles of gas

If pressure decreases:
- equilibrium shifts to the side with the most moles of gas

Question 12

What do you need to talk about when answering a question about equilibrium

Answer 12

• which way is it moving?
• why? (to counteract the change)
• what is going to happen to the yield?

Question 13

Describe rate of a reaction over time

Answer 13

• Rate is faster at the start as there is a bigger concentration of reactants so more frequent collision
• starts steep, starts to flatten at (use data), completely flattens at