The Electrolysis of Copper Sulphate
Aim
Analyse and evaluate the quantity of Copper (Cu) metal deposited during the electrolysis of Copper Sulphate solution (CuSo4) using Copper electrodes, when certain variables were changed.
Results
Voltage across Concentration of solution
electrode 0.5M 1.0M 2.0M
Analysing/Conclusion
The input variables in this experiment are; concentration of the solution and the voltage across the electrodes. The outcome is the amount of copper gained (measured in grams) at the electrodes. By analyzing the graph, we can see the rapid increase of weight gained for the 2.0 molar concentration as the gradient is steeper. Whereas the 1.0 mol and 0.5 mol concentrations increases steadily at a slower rate. This obviously shows that if the voltage increase, the weight also increases. Hence I can conclude; the higher then voltage and concentration, the more copper is produced. The reason for this would be because we used electrolysis. This is used to separate metals from their ores and metal compounds. The electrolyte (solution) contains negative and positive ions. For electrolysis to work there must be the same amount of positive ions to negative ions so that the solution is electrically balanced. A solution of metal compounds can only conduct electricity if it is balanced. The negative ions are attracted to the anode (+ve electrode) and the positive ions (protons) are attracted to the cathode (-ve electrode). The electrolyte effect the amount of atoms attracted.
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Peer Reviews
Here's what a star student thought of this essay
Quality of writing
Spelling, punctuation and grammar all to a good standard. The tone and format of the piece is also excellent.
Level of analysis
The aim is explained clearly but I would like to see some sort of prediction backed up with scientific principles to show the candidates understanding of the science behind the experiment and not just the values. They didn't explain which variables they were changing and why, or why they might keep certain variables constant which would have again showed their understanding through manipulation of the experiment and prediction of the results. The table is good with consistent decimal places although the concentration of solution and what we are measuring is not really clear from the table design. The analysis is very good with high scientific accurate detail and equations. The evaluation is also very good with explanations offered for the possible errors with improvements.
Response to question
A very well done experiment. The only things lacking are a solid introduction and prediction, but this is made up for by a very strong analysis and evaluation of the experiment at the end. The candidate should include a method/diagram of the experiment so they show their understanding of the variables and what might have gone wrong.