Quotes; A compound that conducts when molten or in solution is called an electrolyte. If a pair of electrodes is placed in a solution of an electrolyte, and a source of direct current is connected between them, the positive ions (cations) in the solution move towards the negative electrode (cathode), and the negative ions (anions) move towards the positive electrode (anode),Author; Microsoft Encarta Encyclopaedia 2002.
Half Equations
At the Anode (+):
Cu(s) = Cu2+ + 2e-
What happens here is that the copper at the Anode releases copper ions and electrons, as a result the copper Is reduced. The process which caused this is known as reduction. Reduction is the gain of electrons. In its first state the copper was a liquid. By using Electrolysis we add two negative electrodes, this neutralizes the copper and makes it a solid.
Because in this reaction the sulphate doesn’t move, the water solution subsequently has to be separated.
H O = leaves oxygen and water.
2O – 4e = O (g)
The oxygen is attracted by the positive Anode. The oxygen is oxidised as it loses electrons, this is due to oxidation being the loss of electrons.
Preliminary Test
Before proceeding with the experiment itself, I conducted a preliminary test. This was so I could ensure my variables which were;
Amount of Copper Sulphate
Voltage
Time
Length of Graphite
With the CuSO , I first poured in 150mm into a glass beaker. Later I found this to be insufficient. My group and I found out that the amount of Copper Sulphate was to our surprise also insufficient, this was due to the fact that the graphite rod was not far deep enough in the CuSO solution meaning not enough of the rod was covered to bring about a good reaction.
I changed the amount of Copper Sulphate to 200mm, this proved to be satisfactory.
We began the preliminary test with 1 volt again this wasn’t enough to produce a reaction between the graphite rod and the Copper Sulphate. I decided to start at 2 volts and timed for 5 minutes. By changing the volts to 2, there was enough push to bring a reaction.
Thanks to the preliminary experiment we knew the amount of each variable to conduct the actual experiment.
Method; What we did
Apparatus/Equipment
Power Pack
Graphite Rod
Copper Sulphate (CuSO)
Crocodile Clips
Stop Watch
Glass Beaker
Balance = used to weigh graphite rod
After collecting our equipment and setting up our apparatus, we poured into the glass beaker 200mm of Copper Sulphate.
We set the power pack on 2 volts and waited for 5 minutes, to see whether a reaction had occurred or not.
Faire Test
To make the experiment a faire, there were many things we factors we focused on e.g. amount of Copper Sulphate, size of the graphite rods, keeping them the same weight and length. To ensure we had these things write we measured them using the scale on our glass beakers and for he graphite rods we used a balance.
Conclusion
The graph in which I produced from the given result was a straight line graph. Looking at the graph your able to see how it supports my prediction and hypothesis. From 2 volts to 12 there was a constant increase. Proof of this is shown in my result table.
Evaluation
After carefully analysing my graph I think my results we obtained accurately. With my results I produced a straight line graph, which was one of my statements in my prediction. However there were some anonymous results between 8 volts and 9 volts. This means they were very much below what was expected.
To have achieved what was expected at 8 volts the amount of copper should have been 0.96. At 9 volts the average for the expected amount of copper should have been 1.02.
For reasons why these errors occurred I looked at some factors.
The first factor I looked at was a possibility that the length of the graphite rods might have affected the outcome of the results at the two volts suggesting that the graphite rods were not deep enough in the Electrolyte. Other factors I considered was there might have been a decrease in the concentration of the solution or inaccurate timing.
If any improvements were to be made, I would say, there needs to be an improvement in the efficiency in the equipment provided by the school as I remember some of our power packs not working. During the course of or experiment there seemed to be a shortage or our Electrolyte Copper Sulphate and the accuracy of the balances were poor.
To take the experiment further, in relation to Electrolysis, I could look at the temperature, trying to purify copper or by using current to find out the amount of copper gains and looses in the electrodes.