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Electrolysis: How Does Current Affect The

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Aim: The aim of this investigation is to find out how current affects the amount of copper formed at the cathode, when using copper sulphate solution and graphite electrodes. Pre-test Results: For my pre-test, I have gathered the following results: Current Volume of Copper Sulphate Time Mass of cathode before Mass of cathode after 20.2 mA 50ml3 3 minutes 3.25g 3.27g 0.1A 50ml3 3 minutes 3.11g 3.12g 0.2A 40ml3 4 minutes 3.12g 3.14g 0.4A 25ml3 5 minutes 3.14g 3.17g 0.6A 50ml3 5 minutes 3.17g 3.19g 1A 30ml3 4 minutes 3.21g 3.24g From the pre- test, I have decided: * Time: 5 minutes * Volume of Copper Sulphate Solution: 50 ml3 * Beaker size: 100ml3 * Range of Currents: 0.1A, 0.2A, 0.3A, 0.4A, 0.6A. * Current: Amps I decided to time the reaction for 5 minutes, because with lower currents, not much copper was being deposited, so I decided t time for 5 minutes so that all the different masses could have some copper collected. Using 50 ml3 of copper sulphate solution, more ions would be present in the solution so more ions would go to the electrodes and more copper would be formed. In a 100ml3 beaker, more of the electrodes are covered in the solution, so more copper will form quicker. I decided to use these currents, because there are doubles and triples, so I will be able to find out if the mass and current is directly proportionate to each other or not. ...read more.


So the mass of 0.000621761 mol of copper is: Mol of Copper * Molecular Weight = Mass of Copper 0.000621761 mol * 64g/ mol = 0.039792746g This tells us that 0.039792746g of copper will be formed at the cathode. 0.6A= Time * Current= Charge 300s * 0.6C/s = 180.0 C Charge/Constant = Mol of Electrons 180.0 C/ 96 500 C/ mol= 0.001865284 mol At the Cathode: Cu2+ (aq) + 2e- Cu (s) 2 mol of electrons are needed to liberate 1 mol of Copper, so 0.001865284 mol of electrons will be needed to liberate 0.000932642 mol of Copper. So the mass of 0.000932642 mol of copper is: Mol of Copper * Molecular Weight = Mass of Copper 0.000932642 mol * 64g/ mol = 0.059689119g This tells us that 0.059689119g of copper will be formed at the cathode. From these figures, I can predict the shape of the graph. I predict it will go up in a positive correlation and will be directly proportionate- as the current increases, the mass does. So if the current is doubled, tripled, etc, so will the mass of copper collected. The graph below will show a similar graph as to the final graph: Apparatus: * 100ml glass beaker * 6 wires * 2 crocodile clips * 1 light bulb * 1 stopwatch- hh mm ss.ss * 2 graphite rods (electrodes) * 50ml copper sulphate solution (electrolyte) * 2 elastic bands * 1 small piece cardboard to hold the electrodes * 1 2d.p. ...read more.


Also because the experiment was not carried out all on the same day and equipment may have been different, therefore making a difference. The results were reliable, even though I did have a few errors which were corrected. The results did however show a clear pattern that as the current increased, so did the mass of copper collected. I could improve my method by carrying out the experiment under the same conditions every time I did it, using the same equipment, measuring more accurately and taking a bit more time, so that things would not be rushed. I could also have the room temperature constant, so that if temperature affects the reaction, then it wouldn't have much of a difference. If I were to extend the investigation to make it better, I would keep the Table of results Current- amps Volume of copper sulphate solution- cm3 Time- minutes Mass of cathode before- g Mass of cathode after- g Difference in mass- g Mass of cathode before- g Mass of cathode after- g Difference in mass - g Mass of cathode before- g Mass of cathode after- g Difference in mass- g Average mass- g 0.1 50 5 3.24 3.26 0.02 3.26 3.27 0.01 3.13 3.15 0.02 0.02 0.2 50 5 3.15 3.18 0.03 3.19 3.21 0.03 3.21 3.25 0.04 0.03 0.3 50 5 3.25 3.28 0.03 3.28 3.32 0.04 3.32 3.36 0.04 0.04 0.4 50 5 2.88 2.94 0.06 2.94 3.00 0.06 3.00 3.05 0.05 0.06 0.6 50 5 3.00 3.08 0.06 3.02 3.10 0.08 3.10 3.18 0.08 0.08 ?? ?? ?? ?? Zoya Khan 10L 1354 13228 ...read more.

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