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What factors affect the amount of copper-plated on the cathode by electrodes of copper sulphate?

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What factors affect the amount of copper-plated on the cathode by electrodes of copper sulphate? Introduction: Electrolysis is the decomposition of a substance by passing an electric current. Some substances are strong and others weak, depending on how they can be decomposed. E.g. sodium chloride is a strong electrolyte and water is a weak electrolyte. Oil is not an electrolyte because it does not decompose by passing an electric current. Variables: 1. Time - The longer the electrodes are in the solution the more mass will be lost at the anode and gained at the cathode. 2. Current - With a greater charge, the copper at the anode has to decompose more to give more electrons. 3. Temperature of electrodes - If an electrode gets hot it will expand. 4. Concentration of copper sulphate - The stronger the solution the more copper ions there will be to take electrons from the cathode. Surface area of electrode - When the electrode has a larger surface area there is more surface for the copper ions to dissolve into the solution from, and the greater the surface area the greater the loss in mass at the anode. ...read more.


I will always use 500 ml of copper sulphate solution. The weights recorded for the cathode will be measured by an electronic scale, which is more accurate, and to the nearest milligram. Safety I will ensure a safe test by: * Keeping the glass beakers away from the edge * My hands will be dry at all times when coming into contact with the electricity * The wires will be kept off the floor to avoid tripping up * I will keep a clean area to work with which will minimize accidents and breakages as well Method: I would place 50 ml of copper sulphate in a small beaker. The strength of the copper sulphate would be 0.5M. I am also going to place 2 electrodes in the beaker held by crocodile clips, which would be connected to a power pack. First I will always weigh the electrodes. I will vary the amount of voltage passing through I will start off with 12 and go down to 6 then 3. I will always pass the volts through the solution for 1 minute. I will remove the electrodes and weight them again and record how much copper has bee deposited. ...read more.


Although this was a successful experiment, there were some factors of the experiment, which could have been improved to make it even more successful. One of these factors could have been the electrodes, some were still quite dirty and clearly still had irremovable substances from previous experiments still attached to them. If this experiment were to be repeated for a second time, in need of greater accuracy, it would be very important to have a new pair of electrodes, which have never been used before. 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 supply 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. I found this investigation very interesting and if I were to do this investigation again I would change the variables in this experiment, which may or may not affect the mass of copper deposited onto the cathode, such as changing the concentration or temperature variable. ...read more.

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