Controlling Rates

Question 1

Activated complex

Answer 1

The unstable arrangement of atoms formed at the maximum of the potential energy barrier

Question 2

Why do chemists need to control the rate of reaction

Answer 2

To ensure processes are economical and safe

Question 3

As reactants are used up during the process…

Answer 3

the rate will decrease, and the reaction slows down

Question 4

Average rate

Answer 4

Change in quantity / change in time

gs^-1

Question 5

Relative rate

Answer 5

1 / t

s^-1

Question 6

Collision theory

Answer 6

For a chemical reaction to occur, the reactant molecules must collide with enough energy

Question 7

What is activation energy (Ea)

Answer 7

The minimum kinetic energy required for a reaction to occur

Question 8

Factors that control the rate which reactant molecules collide:

Answer 8

temperature
concentration
pressure
particle size
use of a catalyst

Question 9

For exothermic reactions, ΔH will always be

Answer 9

Negative

Question 10

For endothermic reactions, ΔH will always be

Answer 10

Positive

Question 11

What is the effect of catalysts on activation energy

Answer 11

catalysts lower the activation energy