Investigation into the Factors that Affect the Enthalpy Change During a

Investigation into the Factors that Affect the Enthalpy Change During a Displacement Reaction The Task -------- To investigate the factors affecting the enthalpy change during a displacement reaction. Background Knowledge ==================== In this investigation a displacement reaction will be observed. A displacement reaction occurs when more reactive metal displaces, (or removes) a less reactive metal from a solution of its salt. Also known as chemical bullying because a more reactive metal effectively bullies the original metal out of its compound. In this investigation zinc and copper sulphate will be reacted together. Zinc is the more reactive metal here, so the copper is displaced from the copper sulphate solution. Zinc + Copper sulphate à   Zinc sulphate + Copper Zn (s) + CuSO4 (aq) à   ZnSO4 (aq) + Cu (s) After the reaction it will be observed that the solution will change from blue to clear, colourless. The copper discharged will be observed as a salmon pink deposit in the base of the vessel the reaction occurs in. Reactions like this can be used to purify metals that are low down in the reactivity series. A more reactive metal can simply be added to purify the less reactive metal, leaving it in its pure state. Lead Oxide + Tin à   Lead + Tin Oxide In reality thought this process is hardly ever used, as the more reactive metal is the left in an impure form, and thus must be reduced by an even more reactive metal. As this is not economically viable metals are generally reduced using electrolysis, which leaves them in a pure state, and requires no expensive more reactive metals, just ... ...pacity of the solution (assume this equals 4.2 J/g/degrees Celsius), /T = temperature change (estimated from extrapolation). The results here show the heat energy in each reaction. To calculate the enthalpy change one must account for the respective moles involved in each reaction. To equal out the number of moles simply multiply the results by the respective amounts required to make them all amounts of Joules/1 mole. When this calculation is performed on all the heat energy results enthalpy change can be compared. In an accurate experiment the enthalpy change when copper sulphate solution is reacted with zinc powder should remain constant. By taking into account the number of moles in each equation when multiplying the results will be brought into proportion, so the enthalpy changes should be roughly equal.