5.1

Question 1

How can you speed up or slow down reactions? (1)

Answer 1

By changing the conditions

Question 2

What is the definition of a chemical reaction? (2)

Answer 2

(1) the change in concentration of one of the reactants or products…
(2) with unit time

Question 3

SPEC: Define activation energy. (2)

Answer 3

(1) the minimum energy
(2) that a particle needs to react

Question 4

SPEC: Why do most collisions not lead to a reaction? (2)

Answer 4

(1) either they don’t have enough energy
(2) or they are in the wrong orientation

Question 5

What are the optimum conditions for a fast reaction? (4)

Answer 5

(1) collisions occur with enough energy
(2) correct orientation
(3) lots of particles in a small volume
(4) particles have to be moving fast

Question 6

How does increasing the temperature increase the RoR? (3)

Answer 6

(1) increases the speed of the molecules
(2) which increases the energy of the molecules
(3) which increases the number of successful collisions, as more particles have sufficient energy

Question 7

How does increasing the concentration/pressure of a solution/gas change the RoR throughout the reaction? (6)

Answer 7

(1) more particles are present
(2) collisions = more likely
(3) RoR = increases
(4) overtime, reactants are used up
(5) concentration of reactants = falls
(6) RoR = decreases

Question 8

How does increasing the surface area of solid reactants increase the RoR? (2)

Answer 8

(1) more sites for reaction
(2) more of its particles are available to collide with the molecules

Question 9

In an enthalpy diagram, where does the transition state lie? (1)

Answer 9

(1) at the top of the curve

Question 10

What happens in the transition state? (2)

Answer 10

(1) Some bonds are in the process of being broken
(2) Some bonds are in the process of being formed.