Rates of Reaction

• The rate of a chemical reaction is how fast the reactants are changed into products
• One of the slowest is rusting of iron
• Other slow reactions include chemical weathering - like acid rain damage to limestone buildings
• An example of a moderate speed reaction would be the metal magnesium reacting with an acid to produce a gentle stream of bubbles
• Burning is a fast reaction, but explosions are even faster and release a lot of gas
• You can find the speed of a reaction by recording the amount of product formed
• The steeper the line on the graph, the faster the rate of reaction
• Over time the line becomes less steep as the reactants are used up
• The quickest reactions have the steepest lines and become flat in the least time
• Particles must collide with enough energy in order to react
• Reaction rates are explained by collision theory
• The rate of chemical reaction depends on: 1. The collision frequency of reacting particles. The more collisions there are the faster the reaction is
• The rate of chemical reaction depends on: 2. The energy transferred during a collision. Particles have to collide with enough energy for the collision to be successful
• The minimum amount of energy that particles need to react is called the activation energy
• Particles need the reaction energy to break the bonds in the reactants and start the reaction
• Factors that increase the number of collisions (so that a greater proportion of particles collide) or the amount of energy particles collide with will increase the rate of the reaction