amount of electricity that passes through the system This relationship is shown

Amount of electricity that passes through the system

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amount of electricity that passes through the system. This relationship is shown in the equation: C = At [8] where C is the amount of electricity passing through the circuit, 1 coulumb being transported every second by each ampere. A is the current in ampere and t is time in seconds. 96,500 Coulomb per mole of electron is equivalent to 1 Faraday, which is the electrical charge contained in 1 mole electron. Using this formula, the concentration of the half-cell can be calculated and substituted to the Nernst equation. The purpose of this experiment is to further understand and apply the concepts of electrochemistry and the processes and elements of an electrochemical cell to actual experiments and to determine the spontaneity of reduction-oxidation reactions based on standard reduction potential. Experimental Detail For the first part of the experiment, three half cells were prepared, with cell notations of 3
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Cu 2+ (1M)|Cu, Zn 2+ (1M)|Zn and Fe 3+ (1M),Fe 2+ (1M)|C. The first electrode was prepared by immersing a copper electrode in 1 M CuSO 4 . The second half cell was prepared by immersing a zinc electrode in 1 M ZnSO 4 . Lastly the third half cell was a mix of equal volumes of 2 M FeSO 4 and 2 M FeCl 3 with graphite as its electrode. An iron nail was not used due to the side reaction that might cause rust to form on the nail’s surface: 2 + ¿ →FeO 3 + ¿ → Fe ¿ Fe ¿ [9] Instead, a graphite electrode, which is a semi-conductor, was used. This is made of the electrically inert carbon that would not participate in the reaction. These half cells were then connected with the wires of the volt- meter to a copper half cell prepared in the same manner. A salt bridge was made out of rolled filter paper soaked in saturated potassium nitrate and then each of its ends was soaked in one of the two half-cells. The set-ups for the first part of the experiment is shown in Figure 2. Figure 2. Voltaic Cell Set-up For the second part of the experiment, another 3 half cells were prepared with cell notations Cl - (1 M), Cl 2 | C, Br - (1 M), Br 2 | C, I - (1 M), I 2 | C. Like in the third half cell, a graphite electrode was used. Potassium halide (KX) solutions were electrolyzed by immersing two graphite electrodes into the solution and connecting these to a 1.5 V dry cell which serves as its energy source as shown in Figure 3. This was done for 1 minute, until the halide ions were oxidized to halogens, X 2 . Figure 3. Electrolytic Cell Set-up The prepared mixture of halogens and halide solutions were then connected to the copper half-cell like the set-up in Figure 2. The volt-meter reading for the six voltaic cells prepared were recorded and used in calculations. Results and Discussion The measured voltages of the prepared voltaic cells are tabulated in Table 1. Table 1. Volt-meter Readings Set- up # Cell Notation Volt s 1 Cu|Cu 2+ || Cu 2+ |Cu 0.08 96 2 Zn|Zn 2+ || Cu 2+ |Cu 1.08 3 Cu|Cu 2+ || Fe 3+ |Fe 0.41 4 4 C|Cl - ,Cl 2 || Cu 2+ |Cu 0.46 8 5 C|Br - ,Br 2 || Cu 2+ |Cu 0.26 9 6 C|I - ,I 2 ||Cu 2+ | Cu 0.12 1 4 X - bat
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The potentials measured from the experiment are the potentials of the whole voltaic cell set-ups while the given potential of the reference electrode, Cu 2+ /Cu, is 0.34 volts. From
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