Rates of Reactions

Question 1

Rate of Reaction

Answer 1

Change in concentration per unit time of any one reactant or product

Question 2

The Instaneous rate of reaction

Answer 2

The rate of reaction at any one particular time during the reaction

Question 3

Catalyst

Answer 3

Substance that alters the rate of a chemical reaction but is not consumed in the reaction itself

Question 4

Enzyme

Answer 4

A substance that is produced by a living cell and acts as a biological catalyst

Question 5

Homogenous catalyst

Answer 5

A catalysis in which both the reactants and the catalyst are in the same phase.
I.e. there is no boundary between the reactants and the catalyst

Question 6

Heterogenous catalysis

Answer 6

Catalysis in which the reactants and the catalyst are in different phases. I.e. there is a boundary between the reactants and the catalyst

Question 7

Autocatalysis

Answer 7

Catalysis in which one of the products of the reaction acts as a catalyst for the reaction

Question 8

Catalytic converter

Answer 8

Device in the exhaust system of a motor vehicle which contains catalysts to convert pollutants in the exhaust gases to less harmful substances

Question 9

Catalyst poison

Answer 9

Substance that makes a catalyst inactive

Question 10

Effective collision

Answer 10

One that results in the formation of products

Question 11

Activation energy

Answer 11

Minimum energy that colliding particles must have for a reaction to occur, I.e. the minimum energy required for effective collisions between particles to occur

Question 12

Reaction profile diagram

Answer 12

Graph which shows the change in energy of a chemical reaction with time as the reaction progress

Question 13

Name two metals that would be found in catalytic converter?

Answer 13

1. Platinum

2. Rhodium

Question 14

What are the factors that affect the rate of a chemical reaction?

Answer 14

1. Concentration
2. Temperature
3. Particle size
4. Catalysts
5. Nature of reactants

Question 15

What is the Surface Adsorption Theory of a catalyst?

Answer 15

The accumulation of substances only at the surface of another substance

Question 16

Give 2 reasons why the rate of a chemical reaction increases as the temperature rises

Answer 16

1. There is an increased number of collisions since the moving molecules have more energy at the higher temperature
2. More of the collisions are effective at the higher temperature. i.e. the colliding molecules have the minimum activation energy needed to react