Aim:- To investigate what factors affect the rate of decomposition of hydrogen peroxide.
Hydrogen peroxide + catalyst Water + Oxygen.
Temperature : - If temperature was investigated if it would be very hard to keep the surrounding temperature constant throughout the reaction.
Concentration:- This would be the most appropriate variable as dilutions can be prepared easily and most accurately.
Volume of catalyst:- This is a hard variable to quantify and measure especially if the catalyst is in powder form. Changing the volume of catalyst would also produce too small a change in reaction rate to be able to quantify or make a statement about.
Surface area:- Breaking up a solid into smaller pieces provides a greater surface for collisions to occur between reacting particles. This would be a good variable however again it is very hard and time consuming to measure surface area and to be able to quantify and separate them into groups of size.
Type of catalyst:- This would be a good variable to use but the reasons why the type of catalyst affect the reaction rate are extremely in depth and too difficult to explain fully with current knowledge.
I will therefore be using concentration.
Scientific knowledge and background.
The rate of a reaction depends simply on how often and how hard the reacting particles collide with each other. The basic idea is that particles have to collide in order to react and they have to collide with enough energy to react. Increasing the concentration. Increasing the concentration of peroxide will place more peroxide particles in the same area hence pushing the particles closer together. Increasing the concentration, increases the chance of collisions occurring between reacting particles and hence increases the reaction rate. At the end of a reaction the reaction rate slows down significantly as the reactants get used up throughout the reaction. Therefore the rate of reaction is greatest at the beginning of the reaction as there are more free reactant particles to collide with each other.