= 900 X 64 = 0.30g of copper
193000
= 1050 X 64 = 0.35g of copper
193000
= 1200 X 64 = 0.40g of copper
193000
It is clear from my table, that the longer the electricity is distributed, the more copper is liberated from the to the Cathode. It is lost from and gained to the Cathode.
Apparatus
- 6V power supply
- Emery paper
- Distilled water
- Propanone (For cleaning electrodes)
- Ammeter
- Rheostat (for current regulation)
- Copper sulphate solution (electrolyte)
- Two Copper electrodes.
- Two leads and crocodile clips.
- Digital balance
- Forceps (for handling electrodes)
- Stopwatch
- Drying paper (before ‘weighing’ electrodes)
- 100cm3 beaker
- And most important of all Safety Glasses!!!
Method:
Firstly I will clean the electrodes with emery paper then wash them with distilled water. I will then dip the electrodes in Propanone and dry them. I will use Propanone because it is volatile and so it evaporates very quickly. Electrodes need to be dry so the impurities are taken away and more importantly the surface area is correct which leads to a correct weight. The electrodes I am using are copper because there are two problems with inert graphite. This is the molarity and the weighing difficulties. In a preliminary experiment I found out a couple of interesting points which I know will benefit my chances of getting accurate results. If we use inert electrodes then it means the solution will become weaker as the experiment continues. We would be relying on the solution to produce copper so the more into the experiment we go the less copper will be deposited. The two copper electrodes make this a fair test because it means we will be using the identical solution every time. Using two inert electrodes indicates the gain at the Cathode would have to be measured because there would be no loss at the ( the copper will be coming from the solution ). You see, the problem with weighing gain at the Cathode is very significant. Some of the copper is left at the bottom of the beaker which tells us that the mass gained at the Cathode is not accurate. Also the copper is not tightly fixed to the Cathode therefore some will get knocked off, and lost when moving the electrode.
To know the exact amount of Coulombs I will use a Ammeter to measure it. A Rheostat will be used to control the flow.
I will weigh and record the mass of the electrodes in grams to 2 decimal places. To complete the circuit I will ensure a 6V power supply, at a current of 0.5 A. Now I am ready to begin the experiment. I switch the power and start the stop clock. After 5 minutes I shall switch off the power supply, disconnect the Anode, wash with distilled water, dip in Propanone and dry it before re-weighing and recording the mass of it.
After this I will reconnect the Anode and repeat the same procedure until I have at least 8 readings. I have chosen to record 8 readings just to be completely confident with my results. I want the results to show a clear pattern, so the more recordings I get the better. I will measure the loss of weight at the Anode rather then the gain of weight in the Cathode because weighing the loss will give more accurate results (as I mentioned before).
As is necessary I am trying to use the most accurate measurements. If there are two main points that have to be emphasised these are it. Using copper electrodes rather then inert graphite is one way. The other is weighing the loss on Anode rather than the gain in Cathodes.
To ensure my experiment is a fair test I shall have 3 controlled factors which will not differ. These are the current, the solution and the electrodes. Neither of these factors will change the electrodes with be cleaned the identical way every time and the current will always be 0.5 Amps. My experiment which takes place in the same environment for all of the eight reading. I would be seriously surprised if my experiment is 100% accurate because it should be instigated in a perfect environment which is one that doesn’t allow energy to be given out. However, saying this my results should be accurate by means of ratio.
I expect each reading to be the same distance from each other as the actual reading are.
To enable my experiment to be a safe as possible, I will always be wearing safety goggles and keep my tie tucked inside my shirt all the time whilst the experiment is going on. I will not disturb or be distracted at any time during the experiment and handle all equipment with the utmost respect.
Obtaining and Collecting Data
I believe I have gained sufficient results for me to put into a table. As I have mentioned before the most significant readings are: The Number of Grams Lost at the Anode, and The Amount of Coulombs Transmitted Between Each Reading. I will plot the results of ‘Grams against Coulombs’ on a graph.
I am extremely confident that all of the results are accurate, this is because the same procedure took place for each reading. However, if there is to be a fault in the results this would not be a huge problem because the proportion of the results will be exactly the same which is what is required. The proportion will be the same due to the fact that the experiment was constructed in the same environment for each and every reading. The three controlled factors did not differ at all ( Current, Solution and Electrodes).
I am expecting to find a definite correlation between my Hypothesis and my Results.
Analysing and concluding
The copper was not held tightly to the Cathode. There was a deposit the bottom of the beaker which confirms my reasoning to measure the loss at the rather than the gain at the Cathode. I had to be careful with the recording of the results at the beginning, because I could not recognise the difference between the Cathode and the Anode, so I just had to weigh them both (obviously taking the reading which had decreased from before). The confusion could have easily come about when putting the copper strips back on I could have put the wrong piece of copper in the wrong charge therefore reversing the result. Just so happened that I weighed the two strips one at a time to avoid that sort of predicament, and in retrospect it was definitely the right thing to do. As soon as I figured out which of the electrodes was the negative one () then it became far less complicated. This meant I only had to remove one electrode and clean that electrode then weigh it for every recording instead of doing twice the work for each result.
Now I have my results I shall plot them on a graph. I should have a clearer indication of how successful my experiment was. I am expecting to find a link between my graph and the graph in my hypothesis. At the moment there are still a few suspicions about my results for example, was there too much exothermic reactions taking place? Is the ratio how it should be? Hopefully these questions can be resolved.
Conclusion
I conclude that the amount of electricity does effect the liberation of copper ions during electrolysis. I state this because when the electricity was turned on the copper ions moved towards the negative electrodes and then discharged there. The amount of copper that is lost is proportional to the amount of electricity passed through. Michael faraday this in his law. The law states that the quantity of material formed is proportional to the amount of electricity passed through. My results supports my hypothesis; This is because my results are very similar to my hypothesis. Evidence to support my accuracy is through the graph of the results, which shows my RESULTS LINE being almost identical to my PREDICTION LINE.
I know exactly why all of my results are lower than the predicted ones. This is because the experiment was not constructed in the perfect environment. I must not forget that my predicted results are recordings which would take place in the most exemplary conditions. By this I mean there would be NO EXOTHERMIC REACTION taking place. This certainly is not the case during my actual experiment, where the exothermic reaction that is taking place loses ‘precious’ energy. As energy is lost it means less copper is being transformed. This gives the reason behind the ‘lower’ results that I received with my experiment. However, the main question that needed to answered is that to do with ratio. I can safely say that the ratio is almost identical to my hypothesis. That is what I was most concerned about, however, it did prove not to be an obstacle.
Evaluation
The results of my experiment are almost identical to that my hypothesis in terms of proportionality. The actual figures are slightly different however but this is to be expected. Rather than there being 0.05 g lost of copper every 150 coulombs there was only 0.03/0.04 being lost. This is due to the fact that the environment was not a perfect one, and that is through no fault of my own. The reason for the slight irregularities are that exothermic reactions were taking place, which loses energy before reaching the copper. I am not at all disappointed because by graph proves that the copper lost is proportional to the coulombs transferred. My hypothesis predicted that this was the case so I have hereby proven my theory.
There where a couple of abnormalities during the procedure. The main culprit was the Rheostat. On more than one occasion it did not work, which became very annoying for a period of time. When we did manage to get it working the experiment got smoother and smoother. The other piece of equipment that may have had a bearing on my results is the Analogue Ammeter. The problem was that it did not show the reading to the nearest 0.01(hundredth), only to the nearest 0.1(tenth). It is conceivable that my measurement of electricity could have been a full 0.05 of an Amp higher or lower then the required amount.
In general, there is absolutely nothing to suggest that my experiment was not successfully executed. I firmly believe that with the equipment I had available, in the conditions I had them in, my results are as accurate as they could possibly be. I have extremely distinctive results and this only strengthens the fact that my prediction is correct. If I had to improve my experiment to make my results exactly the same as the ones that I predicted, I would not only move to a more suitable environment, that forbids exothermic reaction taking place, I would have much more Hi-tech apparatus. The stopwatch, for example would stop as soon as the electricity is cut off, if it was operated by a computer, instead we relied on basic hand-eye co-ordination to achieve these results. Of course all the apparatus would be made specifically for its job, if it were to produce results of incredible high standards. I would use as little as I could of human assistance because everybody is capable of making a mistake and it is therefore more prone to error than a computer. Almost everything would be computerised in my new improved experiment.
I conclude that the amount of electricity DOES effect the liberation of copper ions during the electrolysis. The amount of coulombs transferred is proportional to the amount of copper lost at the Anode. The more coulombs transferred therefore means the more copper is lost from the .
If I had to improve the experiment in any way, shape, or form I would attempt to use other variables for example use Current as a variable factor instead of Time. I believe the results would be different, and just as interesting as these have proven to be. Maybe if the experiment was in a better environment, where loss of energy is at its minimum the accuracy could have improved slightly. The accuracy in this experiment was, in my opinion, as good as it could have been. This must be due to the fact that the usage of scientific ideas and planning procedure helped to get the experiment off on the right foot. The priceless information from Michael Faraday and his laws also gave me a head start.
I would like to point out that the safety aspect of this experiment was respected at all times. Safety goggles were always on, and ties were always tucked in. There was never a stage in the experiment where I did not have everything under control.
Dhivesh Patel 11TC