Chemistry Form 5 Chapter 1 236vj

CHAPTER 1 : RATE OF REACTION Rate of reaction is a measurement of the speed of a reaction.Rate of the reaction can be defined as change in volume of gas against time or reducation of a reactant's mass against time. Rate of reaction is inversely propotional to time of reaction.When a reaction takes place , the amount of reactant will decrease while the amount of product will increase.Average rate of reaction is the average rate of reaction over an interval of time. Instantaneous rate of reaction is the rate of rection that happens at any given time.Instantaneous rate of reaction is the rate of rection that happens at any given time. Instantaneous rate of reaction can be obtained from the gradient of the tangent on the graph of the change in amount of reactant or product against time.The steeper the gradient, the higher the rate of reaction. There are five factors affecting the rate of reaction, which are reaction, which are reactant size,concentration,temperature presence of a catalyst and pressure. The smaller the size of reactant, the larger the total exposed surface area.Therefore,the rate of reaction becomes higher.

Table 10.4 Factors affecting the rate of reaction

The more concerntrated a reactant the more perticles there are per unit volume.Therefore, the rate of reaction becomes higher.As the temperature of a reaction rises , particles will have more kinetic energy.Therefore, the rate of reaction becomes higher. A catalyst will increase the rate of reaction.A catalyst will increase the rate of reaction.A catalyst will not change chemically or in amount at the end of a reaction.A catalyst only changes the rate of reaction but not the amount of product formed.

Pressure affects the rate of a reaction of a reactant in gaseous form.The increase in pressure will increase the rate of a rection.Knowledge of the factors affecting the rate of reaction is applied in daily life and in industrial processes such as the Haber Process and the Process.

Collision theory is used to explain the factors that influence the rate of reaction.Effective collision is the collision between particles that can produce a chemical reaction.To produce a reaction,the particles must collide with the correct orientation and have activation energy(minimum energy).

Activation energy is the minimum energy needed for a reactant's partocles to react.An energy profile diagram is a diagram that shows the energy change that occurs during a chemical reaction.Collision frequency is the number of collision that occur in one second.

An increase in collision frequency will increase the effective collision frequency.With this, the rate of reaction becomes higher.Collision frequency will increase with the smaller reactant size,more concerntrated solution,higher temperatures or higher pressures.

Effective collision frequency that achieves activation energy will increase the rate of reaction. A catalyst provides an alternative route for reactions with lower activation energy.