Factors that Affect the Rate of Reaction | Chemistry for Grade 10 PDF Download

Several Factors that can Affect the Rate of a Reaction

• There are several factors that can affect the rate of a reaction. These are:
• Concentration of the reactants in solution or the pressure of reacting gases
• Temperature at which the reaction is carried out
• Surface area of solid reactants
• The use of a catalyst
• Changes in these factors directly influence the rate of a reaction
• It is of economic interest to have a higher rate of reaction as this implies a higher rate of production and hence a more efficient and sustainable process

The Effect of Increased Concentration or Pressure

Graph showing the effect of the concentration of a solution or gas pressure on the rate of reaction

Explanation:

• Compared to a reaction with a reactant at a low concentration, the graph line for the same reaction but at a higher concentration/pressure has a steeper gradient at the start and becomes horizontal sooner
• This shows that with increased concentration of a solution, the rate of reaction will increase 

Effect of Increasing Temperature

Graph showing the effect of temperature on the rate of reaction

Explanation:

• Compared to a reaction at a low temperature, the graph line for the same reaction but at a higher temperature has a steeper gradient at the start and becomes horizontal sooner
• This shows that with increased temperature, the rate of reaction will increase

Surface Area

Graph showing the effect of increased surface area on the rate of reaction

Explanation:

• Compared to a reaction with lumps of reactant, the graph line for the same reaction but with powdered reactant has a steeper gradient at the start and becomes horizontal sooner
• This shows that with increased surface area of the solid, the rate of reaction will increase

Surface Area and Particle Size

Diagram showing that surface area increase as particle size decreases. A 2 cm³ cube has a surface area of 24 cm² and the same cube cut up into 8 cubes has a surface area of 48 cm²

Effect of a Catalyst

Graph showing the effect of using a catalyst on the rate of reaction

Explanation:

• Compared to a reaction without a catalyst, the graph line for the same reaction but with a catalyst has a steeper gradient at the start and becomes horizontal sooner
• This shows that with a catalyst, the rate of reaction will increase

Exam Tip

You should be able to recall how changing the concentration, pressure, temperature, surface area and catalysts affect the rate of reactions