Rates of Reaction

Question 1

What is a Homogeneous Catalysis

Answer 1

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

Question 2

What is a Heterogeneous Catalysis

Answer 2

A Heterogeneous catalysis is a 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 3

What is Autocatalysis

Answer 3

Autocatalysis is catalysis in which one of the products of the reaction acts as a catalyst for the reaction.

Question 4

What is the Rate of Reaction

Answer 4

The rate of reaction is the change in concentration per unit time of any one reactant or product.

Question 5

What is the instantaneous rate of reaction

Answer 5

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

Question 6

What is a catalyst

Answer 6

A catalyst is a substance that alters the rate of a chemical reaction but is not consumed in the reaction

Question 7

What is an enzyme

Answer 7

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

Question 8

What is an example of Autocatalysis

Answer 8

MnO4- + 8H+ +5Fe2+ -> Mn2+ +5Fe3+ + 4H20

Whereby Mn2+ is the catalyst

Question 9

What is an example of a heterogeneous catalysis

Answer 9

Methanol oxidised to methanal using platinum as a catalyst

Question 10

What is an example of an enzyme

Answer 10

Maltase In Maltose-> glucose

Amylase In Starch->sugars(maltose)

Question 11

What is a catalyst called that slows down reactions and give an example

Answer 11

A negative catalyst/inhibitors

Example: Glycerine in Hydrogen Peroxide to slow down decomposition

Question 12

What is an example of a Homogeneous Catalysis

Answer 12

The Iodine Snake/Elephant toothpaste

2H202 —KI—> 2H20 + 02

Question 13

What is the Activation energy

Answer 13

The Activation energy is the 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 14

What is a Reaction Profile Diagram

Answer 14

A Reaction profile Diagram is a graph which shows the change in energy of a chemical reaction with time as the reaction progress

Question 15

What is a Catalytic

Convertor

Answer 15

A catalyst convertor is a device in the exhaust system of a motor vehicle which contains catalysts to convert pollutants in the exhaust gases to less harmful substances

Question 16

What is a catalyst poison

Answer 16

A catalyst poison is a substance that makes a catalyst inactive

Question 17

What is an effective collision

Answer 17

It is one that results in the formation of products

Question 18

Is the energy of the reactants higher or lower than that of the products in an endothermic reaction?

Answer 18

Higher

Question 19

Is the energy of the reactants higher or lower than that of the products in an exothermic reaction?

Answer 19

Lower

Question 20

Describe a catalytic convertor

Answer 20

A catalytic convertor consists of a thin coating of metals platinum, palladium and rhodium on a ceramic or metal ‘honeycomb’ inside a stainless steel case

Question 21

what dangerous gases does a catalytic convertor take in

Answer 21

CO-Carbon Monoxide
NO-Nitrogen Monoxide
NO2-Nitrogen Dioxide
Hydrocarbons

Question 22

What gases does a catalytic convertor give out?

Answer 22

H20-Water
N2-Nitrogen gas
CO2-Carbon Dioxide

Question 23

Explain the surface Adsorption Theory

Answer 23

1. Molecules diffuse towards the surface
2. Vacant D-orbitals to Form temporary bonds with molecules
3. The Higher concentration of the molecules makes it more likely for the molecules to collide(leading to more collisions, more effective collisions)
4. Products form
5. Desorption-products leave the surface

Question 24

List the 5 factors affecting the Rates of Reaction

Answer 24

1. Nature of Reactants
2. Particle Size
3. Concentration
4. Temperature
5. Catalysts