Presentation on theme: "Reaction Rate The rate of a reaction is the speed at which a reaction happens It can be measured as the ' rate of formation of product ' Or the ‘rate of."— Presentation transcript:
Reaction Rate The rate of a reaction is the speed at which a reaction happens It can be measured as the ' rate of formation of product ' Or the ‘rate of removal of reactant ' A reaction will continue until one of the reactants is used up.
Reaction Rate Concentration : Increasing the concentration, increases the probability of a collision between reactant particles because there are more of them in the same volume so more will collide and speed up the rate of the reaction. If there is less of something, there will be fewer collisions and the reaction will probably happen at a slower speed. Less concentratedMore concentrated
Reaction Rate Temperature : When you raise the temperature, the molecules bounce around a lot more (because they have more energy). When they bounce around more, they are more likely to collide. This means they are also more likely to combine. When you lower the temperature, the molecules are slower and collide less. That temperature drop lowers the rate of the reaction.
Reaction Rate Pressure : Pressure affects the rate of reaction, especially when at least one reactant is a gas. When you increase the pressure, the molecules have less space in which they can move. This increases the concentration of molecules which increases the number of collisions. When you decrease the pressure, molecules don't hit each other as often. The lower pressure decreases the rate of reaction. Less pressureMore pressure
Reaction Rate Surface Area: If a solid reactant or a solid catalyst is broken down into smaller pieces, the rate of reaction increases. The speed increase happens because smaller pieces of the same mass of solid have a greater surface area compared to larger pieces of the solid. Therefore, there is more chance that a reactant particle will hit the solid surface and react.
Reaction Rate Stirring: In doing rate experiments with a solid and solution reactant, it is sometimes forgotten that stirring the mixture is an important rate factor. If the reacting mixture is not stirred ‘evenly’, the reactant concentration in solution becomes much less near the solid, which tends to settle out at the bottom of the flask. Therefore, at the bottom of the flask the reaction prematurely slows down distorting the overall rate measurement and making the results uneven and therefore inaccurate. The 'unevenness' of the results is even more evident by giving the reaction mixture the 'odd stir'! You get jumps in the graph!!!
Reaction Rate Time is Money Rate of reaction is important in industry. The faster the reaction can be done, the more economic it is. Most collisions between the reactant particles are unsuccessful. This is because only a few particles have enough kinetic energy to break bonds. The energy required to do this is called the activation energy. The activation energy is reduced by using a catalyst.