An Experiment of Electrolysis and Faraday's Two Laws

During the course of my experiment, I shall attempt to prove Faraday is two laws regarding electrolysis correct. I will attempt to keep my experiment accurate within the limits of human error.

Faraday’s Laws: The mass of a substance produced at an electrode during electrolysis is proportional to the quantity of electricity that has passed. The number of Faradays required to discharge one mole of an ion at an electrode is equal to the number of charges on that ion.

My Investigation investigate the Faraday’s laws I must measure the amount of metal collecting on

In order to the cathode, or more accurately the amount of metal lost by the anode in the experiment that I intend to perform, whilst varying the current passing through the solution and keeping the time constant thereby changing the number of coulombs passing through the solution as: Coulombs = Current * Time able to show whether or not the amount of metal deposited at the cathode (or the amount lost by the anode) is proportional to the quantity of electricity that has passed by plotting a graph of one value against the other, metal produced against number of Coulombs.

This will prove or disprove the first of Faraday’s laws within the I will be limits of experimental error. discharge 1 mole of As: 1 Faraday = 96500 C/mol And this is the required amount to electrons or charged ions, by varying the current and thereby varying the number of Coulombs. By plotting a graph of number of coulombs against the amount of metal removed from the anode, I will be able to see how many coulombs are required to discharge a certain amount of metal in grams.

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By converting the number of grams into the number of moles and dividing the number of coulombs by the number of moles, and dividing the value by two (as copper has a charge of 2+) I will be able to calculate a value for the Faraday and therefore by comparing it to the actual value for the Faraday, test whether or not this value is correct within the limits of experimental error. Experiment Plan I will use a solution of copper sulphate, and although the quantity should make little different to my results, I will use the same volume (300 cm3) of solution. I will take an electrolysis non-rimmed beaker and using clamp stands to prevent the electrodes touching, I will place two pure copper electrodes in the solution and run a current through the same solution to cause copper to be lost from the anode and deposited on the cathode.

I will run the current through the solution for a time of ten minutes for each experiment. I will record both the current passed through and the mass before and after electrolysis of both the anode and cathode. I will weigh both the anode and cathode before and after the experiment and record the results, I will also clean the electrodes using emery paper so that the surfaces are clean and the copper sticks and is lost easily. I will also clean the electrodes using a process of washing them in water, ethanol and propanone in order to remove any loose pieces of copper from the surfaces of the electrodes and making them as clean as possible.

Prediction predict that in my experiment, I will find that when I calculate the number of coulombs by multiplying the current passed through by the time taken, and then plot this against the amount of metal lost at the anode, I will find a good positive correlation and a direct proportionality in accordance with Faraday’s 1st law. I also predict that when I plot the number of coulombs against the amount of metal removed from the anode, a similar direct proportionality will be shown. I also predict that when I divide the number of coulombs by the number of moles of metal lost, I will find that it comes to roughly one Faraday or 96500 C/mol. My Equipment below: Fair Test In I shall set up my equipment as shown order to keep my experiment as fair and accurate as possible: .

I will keep the copper electrodes the same throughout all my experiments. I will use the same copper sulphate solution throughout all my experiments. I will use the same volume of copper sulphate throughout all my experiments. I will keep the time period constant at 10 minutes throughout all my experiments. I will clean the electrodes carefully using emery paper, water, ethanol and propanone before and after each experiment and before weighing the electrodes.

In order to analyse my results I have drawn a graph of current against mass lost at the anode, as I feel that the mass lost at the anode is more accurate than the mass gained at the cathode. This is due to the fact that some of the copper may be lost in the transition between the electrodes, through it not sticking to the cathode and therefore making the results inaccurate.

Although my results are not entirely accurate, I have been able to find a general trend giving me a straight line through the origin. This shows me that the current is directly proportional to the amount of metal removed from the anode, similarly as I kept the time period constant at 10 minutes I can show that the number of Coulombs is directly proportional to the amount of metal removed from the anode by electrolysis. plotting a graph of number of Coulombs against the amount of metal removed from the anode, I will be able to calculate the direct proportionality between the number of Coulombs passed through the solution and the amount of metal removed from the anode.