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Experiment to find out the enthalpy changes that took place for the reaction between copper sulphate and zinc.

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Introduction

Evaluation I conducted an experiment to find out the enthalpy changes that took place for the reaction between copper sulphate and zinc. An enthalpy change of a reaction is the heat exchange with the surroundings at constant pressure. Introduction In this experiment in order to find out the enthalpy change I shall be reacting aqueous copper sulphate with zinc. In this reaction Cu is being reduced and Zn is being oxidised. In this experiment the enthalpy change is exothermic. Enthalpy changes can be both exothermic and endothermic. Exothermic reactions are easily recognised by a rise in temperature. Endothermic reactions require an energy input. Enthalpy is the total energy content of the reacting materials it is given the symbol H. Enthalpy cannot be measured but it is possible to measure enthalpy change when energy is transferred to or from a reaction system. Enthalpy change is given the symbol ?H where ? ...read more.

Middle

?H = 4.18Jg * 50g * 16.5�C = 3448.5J You then need to divide this by the no of moles of zinc used to get the overall enthalpy change. Moles= mass = 2.106 = 0.032 Ar 65.4 3448.5 = 107765 0.032 107765 = 107.77KJ 1000 The overall enthalpy change given out by this experiment is 107.77KJ Limitations and Improvements There were two main limitations in this experiment, mainly the cup and the thermometer. The limitation of the cup was that it was not too well insulated so heat energy was lost more readily to the surroundings. Also there was no top so heat could have escaped through the top. The limitation with the thermometer was the range. By this I mean, when I took a temperature reading the closest I could get was 0.5, i.e. 21.5 31.5. If I had a better range on the thermometer I could get better, more accurate readings. ...read more.

Conclusion

Also I could have had a colorimeter, which could have shown me when the reaction ended. This could have helped me because it would have been a point where I would have recognised when the temperature would start to fall. Another improvement is that I could have done the experiment again and gain another set of results to compare with my original results. Errors and anomalous results. The errors that occurred in this experiment are as follows. When I took a temperature reading my body heat may have interfered with the temperature. Also due to the lack of range on the thermometer I had to use my own guesswork as to what the temperature was when it was between two whole numbers. Also the experiment was not very efficient. By this I mean that a lot of energy was lost to the surrounding as there was a lack of insulation. If you look at my results you will see that there are not any anomalous results. ...read more.

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