sc18, rates of reaction (paper 2)

Question 1

what are the two conditions for a reaction to happen

Answer 1

• reactant particles must collide with each other
• the collisions must have enough energy

Question 2

state the relationship between successful collisions and rate of reaction

Answer 2

the greater the frequency of successful collisions, the greater the rate of reaction

Question 3

what is activation energy

Answer 3

minimum energy needed by reactant particles for a reaction to happen

Question 4

state the relationship between reaction time and rate of reaction

Answer 4

the greater the rate of reaction, the lower the reaction time

Question 5

what are the different factors affecting reaction rates

Answer 5

• concentration/pressure
• tempurature
• surface area:volume ratio

Question 6

how does an increased concentration/pressure affect the rate of reaction

Answer 6

• higher rate of reaction
• more particles in the same volume
• frequency of successful collisions increases

Question 7

how does an increased tempurature affect the rate of reaction

Answer 7

• higher rate of reaction
• particles move faster
• increasing frequency collisions
• energy of collisions increases

Question 8

how does an increased surface area:volume ratio affect the rate of reaction

Answer 8

• higher rate of reaction
• more particles of the reaction are available
• increased frequency of successful collisions

Question 9

what are catalysts

Answer 9

substances that speed up the rate of a reaction time:
- without altering the products
- unchanged chemically
- unchanged mass at the end of reaction
they provide an alternative reaction pathway with a lower activtion energy