C12 - Rate of Reaction (PAPER 2)

Question 1

What is the rate of a reaction

Answer 1

how quickly the reactants turn into the products

Question 2

What are the two ways rate of reaction can be calculated

Answer 2

• how quickly a reactant is used up
• how quickly a product is formed

Question 3

What are the units for rate of reaction

Answer 3

g/s or mol/s

Question 4

What does a steep or shallow gradient mean about rate of reaction

Answer 4

steep - high rate of reaction
shallow - low rate of reaction

Question 5

How do you obtain the mean rate of reaction between two points in time

Answer 5

• measure two points on the line
• subtract the first point from the second
• divide change in mass; volume by the time taken

Question 6

How do you obtain the mean rate of reaction at a specific time

Answer 6

• draw a tangent to the line at the point
• calculate the gradient of the line (change in y over change in x )

Question 7

What is activation energy

Answer 7

the amount of energy reactant particles need to collide and react instead of bouncing apart

Question 8

What effects increase the rate of reaction

Answer 8

• increasing frequency of collisions
• increasing energy of particles

Question 9

What 4 factors increase the rate of reaction
- How do they do this

Answer 9

• increase in temperature means more energy and more collisions due to moving faster
• increase in concentration means more particles, so collisions become more frequent
• increase in pressure means less space between particles so more collisions
• increase in surface area means more particles are exposed, meaning more frequent collisions

Question 10

What are catalysts
- Are they used up
- How do they work

Answer 10

specific substances that can be added to a reaction that increase the rate
- No
- they provide a different reaction pathway that has a lower activation energy so more particles will have enough energy to react, therefore more collisions will result in a reaction