Chemistry reaction rates
Chemistry Coursework: Reaction Rates Aim The aim of this coursework is to investigate how the rate of reaction between magnesium and hydrochloric acid is affected by the concentration of the acid. Background Collision theory describes the way temperature, concentration and surface area of the solid reactant affects the rate of reaction, by affecting collisions between particles. During a reaction, bonds between atoms must be broken before the electrons can move between atoms which results in new molecules being made, this means that for every chemical reaction, a minimum amount of energy is needed to go into breaking these bonds, this is called Activation Energy. If the activation energy is not achieved, then no reaction will take place to make new molecules. In our case, we are investigating the reaction rates between magnesium and hydrochloric acid, where the hydrogen ions are moving on their own in the water so the only bonds that are needed to be broken are those holding the magnesium atoms together, the hydrogen ions must collide with the magnesium atoms with enough energy so that the bonds can be broken and so the hydrogen ions can take electrons from the magnesium atoms. If the colliding molecules have enough energy, the reaction will occur and so the bonds between the atoms will be broken which result in the new molecules being formed. If the colliding molecules do not have enough energy, then no reaction will take place, and so the bonds will not get broken and new molecules will not be made, the molecules will simply bounce off each other. ... Different conditions can affect the rate of reaction. ... At a higher concentration collisions are again more frequent, as there are more reactant particles in the liquid, so in theory, if you double the number of particles, the number of collisions will double and so also the reaction rate. ... Rate of reaction can also be increased by adding a catalyst, but there is not one for this reaction. In this experiment, the magnesium and the hydrochloric acid will react to form magnesium chloride and the actual reaction will give off hydrogen. ... The ideas stated above are shown in the diagrams on the next page: Prediction I predict that as the concentration of the acid increases, the reaction rate will also increase. I also predict that the reaction rate will be directly proportional to the concentration, meaning that they will have a linear relationship, which will result in the graph being a straight line through the origin.