Rates of Reaction :: GCSE Chemistry Coursework Investigation

An Experiment to show the reaction between Hydrochloric acid and Calcium Carbonate Introduction Hydrochloric acid + Calcium Carbonate Calcium Chloride + Carbon Dioxide + Water 2HCl(aq) + CaCO3(s) CaCl2(aq) + CO2(g) + H20(l) In this experiment we will be investigating the variables that can affect the speed of reaction between hydrochloric acid and calcium carbonate. During this experiment carbon dioxide is produced. This is what we are going to use to record the speed of reaction, for the faster the reaction the faster carbon dioxide is produced. Variables ========= A variable affects the rate of reaction between a number of chemicals. For a reaction to occur the particles have to collide with sufficient energy to break the bonds between them. This amount of energy needed is called Activation energy. In a reaction, only the particles with energies above the Activation Energy will cause a reaction. The different variables that could be used are: Text Box: Surface Area When a solid reacts with a liquid or gas, the surface area of the solid particles makes a difference to the speed of the reaction. From the diagram you can see that the three smaller particles have a larger surface area all together (shown as blue) than the larger particle and so will react faster. There are more calcium carbonate particles on the the concentration of the hydrochloric acid Text Box: surface for the acid to react with. Powders of a Calcium carbonate react even faster as the of calcium carbonate particles showing to react with the acid particles is even greater. Crushing up the solid in an experiment can make a long experiment a lot faster and more violent. The reason that, with a larger surface area a solid reacts faster is that there are more particles showing for the liquid or gas to react with. Temperature =========== This is one of the most effective ways of speeding up the rate of a reaction. From heating the chemical you are transferring energy into the particles. When particles do collide, they are more likely to react, rather than just bounce off each other, if they are moving faster. When the particles have more energy they collide more often and with more force with the other chemical. With more collisions and with a larger force it is more likely that the collisions will be successful. This means that the rate of reaction will be greater. change in heat can change the rate of the reaction. The first curve on the graph shows a reaction when the chemicals involved are of a low