Rates of Reaction

• The activation energy is the minimum energy required for a reaction to occur
• A catalyst is a substance that increases the rate of a chemical reaction without being used up
• Collision theory:

  In order for a reaction to occur, particles must collide and have a minimum amount of energy - known as the activation energy
• Factors affecting the rate of reaction:

  • Concentration of solutions
  • Temperature
  • Surface area of solid reactants
  • Catalyst
• When the concentration of an acid is increased, there are more particles in a given volume. This results in more collisions and therefore more successful collisions in a given time, increasing the rate of reaction.
• When the concentration of an acid is decreased, there are less particles in a given volume. This results in less collision and therefore less successful collisions in a given time, decreasing the rate of reaction.
• When particle size is small, (greater surface area), more particles are exposed to the hydrochloric acid. This means there will be more collisions, more successful collisions in a given time and the rate of reaction will increase.
• When particle size is large, (smaller surface area), less particles are exposed to the hydrochloric acid. This means there will be fewer collisions, fewer successful collisions in a given time and the rate of reaction will decrease.
• When the temp is increased, particles have more energy and move faster. This means there will be more collisions, more successful collisions in a given time and therefore rate of reaction will increase.
• When temperature is decreased, particles have less energy and move slower. This means there will be fewer collisions, fewer successful collisions in a given time and therefore rate of reaction will decrease.
• A catalyst provides an alternative reaction pathway with lower activation energy which leads to an increase in successful collisions in a given time therefore increases rate of reaction.