CHEMISTRY IGCSE -CHAPTER 7 SIR.MUHAMMAD ABDUL MAGEID

1. Sir. Muhammad Abdul Mageid
CIE - IGCSE Chemistry
Chapter 7 CHEMICAL REACTIONS
7.1- Rate (speed) of the Reaction

2. Contents
7.2 Revisible Reaction
7.1 Rate (speed) of the Reaction
7.3 Redox Reactions
Saturday, September 12,
2020
Sir. Muhammad Abdul Mageid

3. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid
Collision Theory
 In order for a reaction to occur reactant particles must collide .
 Not all collisions between reactants succeed in making products.
 Only those collisions with sufficient energy to break the bonds
in the reactants will lead to a reaction.
 A successful collisions is one where reactants react and products are formed
 The minimal amount of energy a collision needs to be successful is called
The Activation Energy
 If the reactants collide and have an energy less than the activation
energy, then no reaction occurs.

4. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid
Collision Theory
 For substances to react , their particles:
1- must collide
2- must collide with enough energy to break existing bonds
 The higher the number of successful collisions
per unit time , the higher the rate of reaction
Rate of the reaction
 Is the concentration of reactant used up , or product made , in a given
time
 Units of rate : 𝒎𝒐𝒍/𝒅𝒎 𝟑
. 𝑺−𝟏

5. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid
Rates of Reaction Factors (Factors affecting
rate)
Effect of Concentration
Effect of Temperature
Effect of Surface Area
Catalyst
Pressure in a gaseous system

6. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid
Effect of Concentration
Explanation:
•Increase in the concentration of a solution, the rate of reaction will increase
 This is because there will be more reactant particles in a given volume, allowing
more frequent and successful collisions per second, increasing the rate of
reaction

7. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid
Effect of Surface Area (Particle size)
Explanation:
•Increase in the surface area of the solid(Decreasing the particle size),
the rate of reaction will increase
 This is because more surface area particles will be exposed to the other reactant
so there will be more frequent and successful collisions per second, increasing the
rate of reaction

8. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid
Effect of Surface Area (Particle size)

9. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid
Effect of Temperature
Explanation:
•Increase in the temperature, the rate of reaction will increase
•This is because the particles will have more kinetic energy than the
required activation energy, therefore there will be more frequent and successful
collisions per second, increasing the rate of reaction.

10. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid
Using a Catalyst
Explanation:
 Catalysts reduce the activation energy as they create alternative pathways
requiring lower activation energy, allowing more successful and frequent
collisions.
•This shows that when a catalyst is used, the rate of reaction will increase.
 A CATALYST : is a substance which speeds up a chemical reaction , but
remains chemically unchanged at the end

11. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid
Using a Catalyst

12. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid
Explosive Combustion
•Explosive combustion occurs when there are many fine particles in the air.
•Many industrial processes such as metal working, coal mining or flour milling
produce very fine and tiny particles.
•These particles have a very large surface area and are combustible in air.
•Even a small spark may cause them to ignite and since the surface area is so large,
the rate of reaction can be incredibly fast, hence they are explosive.
•Methane gas mixed with air in coal mines can also form an explosive mixture.

13. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid

14. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid

15. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid

16. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid

17. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid

18. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid

19. Saturday, September 12,
2020
7.1 Rate (speed) of the Reaction
Sir. Muhammad Abdul Mageid