Effect of increasing charge on Mass of Copper Deposited.

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James Kuspisz

Chemistry Coursework                                                          

Effect of increasing charge on Mass of Copper Deposited



  • I will fist weigh the cathode
  • I will then set up the apparatus as shown in the diagram
  • Then switch the power pack on
  • I will wait 10 minutes and then weigh the cathode, I will do this for 50 minutes every 10 minutes

My Independent Variable is the Charge

My Dependent Variable is the Mass of the cathode

The controlled variables are the concentration of Copper sulphate and the temperature


I can predict that there will be a positive coloration between the increase of charge and the amount of copper produced at the cathode.

Scientific Explanation:

Current is the flow of electrons in a circuit - in the case of electrolysis the flow is towards the cathode and away from the anode. Within the solution, the current flows because of the presence of negative and positive ions. Copper sulphate is an ionic salt, which contains no free electrons. However, it does contain ions (which are charged particles) fixed in a crystalline structure. When copper sulphate is dissolved, the copper sulphate solution becomes an electrolyte because the ions become free to move and they can conduct electricity.

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At the cathode, the copper ions, being more reactive than the hydrogen ions are deposited whilst the hydrogen ions remain in solution. At the anode, the copper atoms from the copper anode give up their two electrons to make them stable. The electron flow in the electric current back to the power supply and the anode dissolves.

When the current is increased, more electrons are at the cathode attracting copper ions, which are positively charged and form a layer of copper atoms. At the anode, more copper dissolves into the solution releasing its electrons to flow back to the power ...

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The method is used with 'I' and should be non-personal to appear more professional in scientific manner. Otherwise, spelling, grammar and punctuation are good throughout. The layout of the piece is done well with clear well define subheadings.

The diagram is easy to read and clearly set out. The candidate does not state what effect changing other variables will have on the experiment or why they have kept the variables constant which would have showed deeper understanding of the principles behind the experiment. The prediction and scientific background to it is done very well with good scientific depth and understanding showed. The apparatus is explained clearly with function so anyone reading could repeat the experiment themselves. Decimal places are inconsistent in the table and they should be kept consistent in order to make their calculations later more accurate. Their improvements and analysis of results is also done very well.

The experiment is laid out very well. The candidate shows deep analysis of and focus on the question which leads to a well thought out experiment. A graph to display their results would have been a different format to display and interpret results from. The candidate could have gone into greater depth about other factors which may have affected the experiment and have accounted for them to increase their level.