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The aim of this experiment is to discover how the rate of electrolysis is affected by the level of voltage.

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Aim The aim of this experiment is to discover how the rate of electrolysis is affected by the level of voltage. Possible Variables * Size of electrodes * Level of voltage * Time * Distance between electrodes * Molarity/Concentration of Electrolyte * Temperature of Electrolyte Plan As a group we have decided that our variable will be the level of voltage. We came to this decision because it will give us accurate results and a good range. For our experiment, we shall use the following pieces of equipment and apparatus: * 1 Power pack with adjustable voltage * 2 wires * 1 beaker * Copper sulphate solution (CuSO4(aq)) * 2 copper electrodes of equal weight (Cu(s)) * 2 crocodile clips * Top pan balance * Stop Watch (to time 5 minutes) Diagram Firstly we shall weigh each copper electrode and record their weights. Secondly, we shall set up our equipment as shown in the diagram. We shall then turn on the power pack, and wait for five minutes and then turn the power pack off. The electrodes will then be weighed again and the new weights recorded. We shall then repeat this process using a higher voltage. The voltages we shall use are 2, 4, 6, 8 and 10 volts. ...read more.


to form cations in the solution which are then attracted to the cathode as detailed above. 2) Therefore the mass of copper gained by the cathode exactly equals that lost by the anode. 3) Electrolysis occurs at a faster rate when a greater voltage is passed through the electrolyte because, if there is a higher voltage that means that electrons are passing through the circuit at a greater speed, so electrolysis reaction can occur faster and the whole process is speeded up. Method Our experiment went ahead as detailed in my plan. Results Table 1 Voltage (v) Cathode's weight after 5 minutes of electrolysis (grams) Anode's weight after 5 minutes of electrolysis (grams) 0 1.5 1.5 2 1.59 1.43 4 1.70 1.34 6 1.85 1.16 8 2.10 0.90 10 2.52 0.51 Results Table 2 Voltage (v) Cathode's weight after 5 minutes of electrolysis (grams) Anode's weight after 5 minutes of electrolysis (grams) 0 1.5 1.5 2 1.57 1.42 4 1.69 1.33 6 1.84 1.15 8 2.08 0.93 10 2.52 0.48 1st Results 2nd Results Voltage (v) Cathode's average weight after 5 minutes of electrolysis (grams) Anode's average weight after 5 minutes of electrolysis (grams) 0 1.5 1.5 2 1.58 1.425 4 1.695 1.335 6 1.845 1.155 8 2.09 0.915 10 2.505 0.49 Results Table 3 Results Table 4 Voltage (v) ...read more.


It is likely that the copper used in our experiment was not pure and therefore this would account for the very slight anomalies in the results. (i.e. direct proportion was approximate) * Another factor which may have affected the overall outcome of the investigation may have been the fact that the practical work of the investigation was carried over from lesson to lesson, meaning that variables such as the concentration or the amount of the Copper Sulphate solution could have changed between lessons. To overcome this problem, a stock solution of Copper Sulphate should have been made so as the concentration remained the same at all times. The same electrodes and equipment should have been used throughout. Also, when weighing, the same electrical balance should have been used as there may have been slight differences between the two balances. This is what could explain the slight anomalies in the graph. Despite the fact that my results seem to be quite conclusive, there is not enough evidence to prove my predictions are absolutely plausible. For this to be possible, one would need to repeat the experiment hundreds of times. It would also be necessary for other people to carry out the experiment and achieve the same pattern of results. I did not find any major anomalies in my results; this can be seen by the uniformity of my graph lines. Alastair Bealby Chemistry Coursework Page 1 ...read more.

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