==Collision Theory== [image:http://i.imgur.com/4VvsKf1.gif] In order for a chemical reaction to occur reactant particles must collide. In these collisions bonds may be broken and new bonds may be formed. The collision results in a new substance (the product) being formed. In order for a collision to be successful the reactant particle must collide with sufficient ''kinetic energy'' and with the ''correct orientation'' in order to break existing bonds within the reactants. The rate at which a reaction proceeds depends on the number of successful collisions per second. ==Rate of Reaction== The rate of reaction can be measured by: *measuring how quickly a product is formed *measuring the how quickly a reactant is 'used up' ===The graph below shows the progression of a chemical reaction with time. === [image:http://i.imgur.com/7yuN71H.png?2] *Initially (first 10s) there are a lot of reactant particles (purple) so collisions are frequent and product particles (green) are formed quickly. This is shown by the steep slope of the graph which represents a rapid increase in product / decrease in reactant. *After a while there are fewer reactant particles. This means collisions and therefore product is formed more slowly. The slopes of the graph flatten indicating the rate if reaction has decreased. *Eventually no more reactant particles will remain and so no more product is formed. The lines on the graph become completely flat (horizontal) indicating the reaction has stopped.