Problem: Electricity produced in a galvanic cell

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Problem: Electricity produced in a galvanic cell by Mind Map: Problem: Electricity produced in a galvanic cell

1. What is a galvanic cell

1.1. Galvanic cells are electrochemical cells that produce energy. In a galvanic cell, there are 2 half cells which are connected in a circuit. This connection allows an oxidization reaction and a reduction reaction to occurs. In this reaction, an electro-potential difference is created and a voltage is produced which can be used to power many things. A galvanic cell is normally referred to as a battery.

1.2. In a simple 2 half-cell, galvanic cell, 2 electrodes (metals) are placed into salt electrolyte ionic solutions of each type of electrode metal which conduct electricity. For example, a copper electrode will be placed in an electrolyte solution of copper sulfate. One of these electrodes is called the anode, the anode is the more reactive metal out of the two electrodes and the other one is the cathode. As per the diagram on the left, each electrode is inserted into a different electrolyte and then connected via a voltmeter to determine the potential difference of the reaction. At the anode, an oxidation reaction to occurs whilst at the cathode a reduction reaction occurs this causes a transfer of electrons from the anode to the cathode. Without the salt bridge, the reaction would cause a neutralization of the electrolyte solutions immediately and no continuous voltage could be produced. The salt bridge, a piece of filter paper coated in a non-reactive salt solution creates a circuit and allows for a continuous electron flow until the electrodes become nonreactive.

1.3. See Figure 1, for a diagram of a galvanic cell

2. Safety Considerations

2.1. Safe disposal of heavy metals

2.1.1. To ensure no heavy metals are released into the sewerage system, they will be collected and provided to the Lab Staff.

2.2. Safe disposal of electrolyte solutions

2.2.1. To ensure that the electrolytes being used have no threat to the environment, they will be collected and provided to the LAB staff.

2.3. PPE will be worn

2.4. Method of experiment will be accessed and approved by science teachers

3. Independent Variable Ideas

3.1. Concentration of the electrolytes

3.1.1. Taking the supplied electrolyte solutions and diluting them with different amounts of distilled water. To complete this process the equation C1V1 = C2V2 can be used to calculate the amount of electrolyte needed. If this was tested, a volumetric pepette must be used for accuracy.

3.2. Change the concentration of the salt bridge

3.2.1. Instead of changing the concentration of the electrolyte, the concentration of the solution in which the salt bridge is soaked in could be varied to investigate the impact this has on the voltage.

3.3. Temperature of the electrolytes

3.3.1. As the temperature of the electrolyte solution is increased there is a greater amount of kinetic energy within the reaction and therefore it should theoretically get faster. The altering of the electrolytes temperature could be achieved through the submersion of the beaker holding the electrolyte in an ice bath or a hot water bath.

3.3.2. Unfortunately this idea is extremely hard to execute as it is near impossible to set an exact temperature for the electrolyte solution. And therefore it will not be tested.

3.4. Changing material of electrodes and therefore varying the electronegitivity

3.4.1. By altering the material od the electrodes the electronegativity which is a measure of the tendency of an atom to attract a bonding pair of electrons can be changed and the impact of this change can be tracked.

3.4.2. A control metal, magnesium can be used and tested with a variety of metals that include zinc , copper, iron, aluminum, magnesium, lead.

3.4.3. The disadvantage to testing this is that it is extremely difficult to keep the surface area of all the metals constant.

4. Dependent Variable Ideas (Things you measure)

4.1. Electrical potential difference produced

4.1.1. With the use of a voltmeter or a setting on the electric multi-meter, the voltage that is being produced by the redox reactions can be measured.

4.1.2. The advantage to measuring the potential difference is that there are standard theoretical values for what the potential difference should be. See Figure 2

4.2. Electric current of the system

4.2.1. With the use of an ammeter or a setting on the electric multi-meter, the ampere that is being produced by the redox reactions can be measured.

4.2.2. The advantage to measuring the ampere is that the digital multi-meter will provide a more accurate result then if the voltage is measured.

4.2.3. The disadvantage of measuring the ampere is that there are not theoretical values available to compare our results to.

4.3. Mass of the electrodes before and after the chemical reaction

4.3.1. It is known that the electrode in the cathode will gain in mass, but the electrode in the anode will decrease in mass. This change in mass can be used to determine the ability of the galvanic cell.

4.3.2. This idea is flawed and should not be attempted because it is not possible to ensure that each electrode has the exact same surface area and therefore the mass difference will be to great to measure.

5. Diagrams and Other Information

5.1. Figure 1: Diagram of a galvanic cell

5.1.1. Link to Source: https://glossary.periodni.com/glossary.hp?en=galvanic+cell

5.2. Figure 2: Standard Oxidation Potentials

5.2.1. Link to Source: http://ch302.cm.utexas.edu/echem