Kinetics

Question 1

what does activation energy mean

Answer 1

• the minimum energy required for a reaction to occur

Question 2

how is rate of reaction defined

Answer 2

• change in concentration/time

Question 3

what 4 factors can affect rate of reaction

Answer 3

• concentration
• pressure
• surface area
• temperature

Question 4

how does increasing concentration/pressure affect the rate of reaction

Answer 4

• it increases the number of reactant particles in a given volume and so increases the frequency of collisions between particles, therefore there will be more frequent successful collisions

Question 5

how does increasing surface area affect the rate of reaction

Answer 5

• this increases the number of reactant particles available for collision and so increases the frequency of collisions between particles, therefore higher frequency of successful collisions

Question 6

how does increasing temperature affect the rate of reaction

Answer 6

• particles have more energy at higher temperature. this leads to many more particles having ≥ energy than activation energy. therefore more successful collisions in a given time

Question 7

what does the Maxwell Boltzmann (MB) distribution show?

Answer 7

the distribution of molecular energies within a sample

Question 8

why does the MB curve start at the origin

Answer 8

• there are 0 particles with 0 energy

Question 9

why does the MB curve not touch the x axis (asymptote)

Answer 9

• there will always be some particles with very high energy

Question 10

what does the peak of the MB curve show

Answer 10

• the most probable energy (the energy value most particles in the sample are likely to have)

Question 11

what is the area under the MB curve equal to

Answer 11

• the amount of particles in the sample

Question 12

how does the MB curve shift when temperature is increased

Answer 12

• shift to the right and down
• asymptote is shifted up

Question 13

how does a catalyst work

Answer 13

Provides an alternative route with a lower activation energy so more particles have more than or equal to the energy required for the reaction to occur

Question 13

how does the MB curve shift when temperature is decreased

Answer 13

• shift to the left and up
• asymptote is shifted down

Question 14

what is a catalyst

Answer 14

• a substance which increases the speed of a reaction, without being changed or used up in the reaction

Question 15

how does the MB curve change when a catalyst is introduced

Answer 15

• the activation energy line shifts back ( lower Ea )