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Once cleaned wipe with tissue soaked in propanone. From this point the electrodes can no longer be touched by the paddles, this is to protect from contamination.
- Weigh the electrodes to obtain a starting mass.
- The apparatus is to be set up as in the diagram.
- Use the Rheostat to set the first current (e.g. 0.5 A).
- Connect the circuit leave for a set amount of time (e.g. 5 minutes).
- Once time is up disconnect circuit and remove electrode making sure not to touch them or knock off any copper.
- Lightly rinse under water, and then dry using a Bunsen burner on jet flame. (This is to prevent soot from adding extra mass).
- Hold electrode high above flame to prevent oxidisation.
- Once dry re-weigh electrodes and repeat with new variable.
Reliability
To make this test as reliable as possible use the same electrodes each time and use the same solution. The time that each current is run for should also be kept constant.
Preliminary Work
Using background knowledge that Q=IT:
Q is Charge in Coulombs
I is Current in Amperes
T is Time in Seconds
And the relative mass of Copper is 64. With this information it became possible to predict what a perfect set of results should be:
Preliminary Prediction
Graph Of Preliminary Prediction Of Copper Transferred
Results
Due to time constraints my readings had to taken in two parts. Between the two parts the electrodes were cleaned, and at the start of the second set of readings the experiment was started as if for the first time. This is indicated in my table of results.
Analysis
From the graph it become obvious that the experiment failed. There are no trends or patterns in the graph.
Conclusion
The evidence from my graph is in no way able to support my prediction. However, my preliminary results fully support it. In theory my prediction is right, but in practice it is near impossible to give supporting evidence.
Evaluation
My experiment was performed under very basic conditions. From the preliminary work I can see that it is not my prediction that is wrong. I believe that given perfect lab conditions and enough time I could prove my prediction right.
In my experiment I lost a lot of copper in the electrolyte. I could improve my experiment by filtering the electrolyte each time and weighing the filtrate with the paddles this would prevent loss of mass.
When drying the paddles I sometimes oxidised the copper and this added mass. In future the paddles could be dried by different means such as a hairdryer on a very low heat.
It took about 30 seconds to set the right current, as this is 10% of the total time this could have an effect on the amount of copper that was transferred. To overcome this problem, a digital resistor could be used that automatically sets the amount of current.
