21+Electrochemistry

=Objectives= Key concepts for section one: -for any two metals in an activity series, which metal is more readily oxidized? -what type of chemical reaction is involved in all electrochemical processes? -how does a voltaic cell produce electrical energy? -what current technologies use electrochemical processes to produce electrical energy?

Section two: -what causes the electrical potential of an electrochemical cell? -what value is assigned to the electrical potential of a standard hydrogen electrode? -how can you determine the standard reduction potential of a half cell? -how can you interpret the cell potential of a redox reaction in terms of the spontaneity of the reaction?

Section Three: -how do voltaic and electrolytic cells differ? -what products are formed by the electrolysis of water? -what oxidation and reduction reactions occur during the electrolysis of brine? -how are electrolytic cells used in metal processing?

=Outlined Notes= Chapter 21 Electrochemistry

I. Electrochemical Cells (Section One) A. Electrochemical Processes 1. Chemical processes can either release energy or absorb energy. 2. It has many applications in the home and in industry. 3. Biological systems also use electrochemistry to carry nerve impulses. 4. A Spontaneous Redo Reaction a. For any two metals in an activity series, the more active the metal is the more Readily oxidized. 5. Redox Reactions and Electrochemistry a. __electrochemical process__- is any conversion between chemical energy and electrical energy. b. All electrochemical processes involve redox reactions. c. if a redox reactions to be used as a source of electrical energy, the two half- reactions must be physically separated. d. an electric current can be used to produce a chemical change. e. __electrical cell__- is any device that converts chemical energy into electrical energy or electrical energy into chemical energy. Redox reactions occur in all electrochemical cells. B. Voltaic Cells 1. in 1800, Italian physicist Alessandro Volta built the first electrochemical cell that could be used to generate a direct electric current. 2. __voltaic cells__ – are electrochemical cells used to convert chemical energy into electrical energy. 3. Electrical energy is produced in a voltaic cell by spontaneous redox reactions within the cell. 4. We use a voltaic cell every time we turn on a flashlight or a battery powered calculator. 5. Constructing a Voltaic Cell a. __half cell__ – is one part of a voltaic cell in which either oxidation or reduction occurs. –a typical half cell consists of a piece of metal immersed in a solution of its ions. b. the half cells are connected by a __salt bridge-__ a tube containing a strong electrolyte, often potassium sulfate. Salt bridges usually are made of agar, a gelatinous substance. A porous plate may be used instead of a salt bridge. This allows ions to pass from one half cells to the other but prevents the solutions from mixing completely. A wire carries the electrons in the external circuit from the zinc rod to a copper rod. c. __electrode-__ is a conductor in a circuit that carriers electrons to or from a substance other than a metal. The reaction at the electrode determines whether the electrode is labeled as an anode or a cathode. d. __anode-__ the electrode at which oxidation occurs. Negative electrode e. __cathode-__ the electrode at which reduction occurs. Electrodes are consumed at the cathode. Positive electrode. The moving electrons balance any charge that might build up as oxidation and reduction occur.

See Page 666 to see a good example of how a voltaic cells works.

C. Using Voltaic Cells as Energy. 1. Current technologies that use electrochemical processes to produce electrical energy includes dry cells, lead storage batteries and fuel cells. 2. Dry Cells a. __dry cell__- is a voltaic cell in which the electrolyte is a paste. A type of dry cell that is very familiar to you is the common flashlight battery, which is not a true battery. b. in an ordinary dry cell, the graphite rod serves only as a conductor and does not undergo reduction, even though it is a cathode. Dry cells of this type are not rechargeable because of the cathode reaction is not reversible. In the alkaline battery, the reactions are similar to those in the common dry cell, but the electrolyte is a basic KOH paste. 3. Lead storage batteries. a. __battery-__ is a group of cells connected together. A 12-V car battery consists of six voltaic cells of lead grids. Each cells produces about 2 V and consists of lead grids. b. when a lead storage battery discharges, it produces the electrical energy needed to start a car. 4. Fuel Cells. a. __fuel cells-__ are voltaic cells in which a fuel substance undergoes oxidation and from which electrical energy is continuously obtained. They do not have to be recharged. They can be designed to emit no air pollutants and to operate more quietly and more cost effective than a conventional electrical generator. b. since the 1960 astronauts has used fuel cells as an energy source aboard space craft. They release no pollutants. But they are too expensive for general use.

II. Half-Cells and Cell Potentials (Section Two) A. Electrical Potential 1. __electrical potential- __of a voltaic cell is a measure of the cell’s ability to produce an electric current. 2. Electrical potential is usually measured in volts (V) 3. The potential of an isolated half-cell cannot be measured. 4. The electrical potential of a cell results from a competition for electrons between two half-cells. 5. The half-cell that has a greater tendency to acquire electrons will be the one in which reduction occurs. 6. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Oxidation occurs in the other half-cell as there is a loss of electrons. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">7. __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">reduction potential- __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';"> the tendency of a given half-reaction to occur as a reduction <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">8. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">the half-cell in which the reduction occurs has a greater reduction potential than the half cell in which oxidation occurs. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">9. __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">cell potential- __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">the difference between the reduction potentials of the two half cells Cell Potential = (Reduction potential of half cell in which reduction occurs) – (Reduction potential of half cells in which oxidation occurs. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">OR E cell = E red – E oxid  <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">B.  <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Standard Cell Potential <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">1.  __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">standard cell potential- __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';"> (E cell) is the measured cell potential when the ion concentrations in the half cells are 1M, any gases are at a pressure of 101 kPa, and the temperature is 25°C. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">2. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">The symbols E red and E oxid represent the standard reduction potentials for the reduction and oxidation half cells, respectively. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">3. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">The relationship for cell potential is E cell = E red – E oxid <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">4. __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">standard hydrogen electrode- __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">is used with other electrodes so the reduction potentials of the other cells can be measured. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">5. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">The standard reduction potential of the hydrogen electrode has been assigned a value of 0.00 V. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">C. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Standard Reduction Potentials <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">1. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">a voltaic cell can be made by connecting a standard hydrogen half cell to a standard zinc half cell. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">2. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">To determine the overall reaction for this cell, first identify the half cell in which reduction takes place. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">3. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">in all electrochemical cells, reduction takes place at the cathode and oxidation takes place at the anode. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">4. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">You can determine the standard reduction potential of a half cell by using a standard hydrogen electrode and the equation for standard cell potential. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">D. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Calculating Standard Cells Potentials <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">1. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">to function, a cell must be constructed of two half cells. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">2. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">the half cell reaction having the more positive (or less negative) reduction potential occurs as a reduction in the cell. It is possible to write cell reactions and calculate cell potentials for cells without actually assembling them. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">3. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">IF the cell potential for a given redox reaction is positive, then the reaction is spontaneous as written. If the Cell is negative, then the reaction is nonspontaneous. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">4. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">This latter reaction will be spontaneous in the reverse direction, however, and the cell potential will then have a numerically equal but positive value.

III. Electrolytic Cells (section three) <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">A. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Electrolytic vs. Voltaic cells <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">1. __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">electrolysis- __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">the process in which electrical energy is used to bring about such a chemical change. (some examples are silver plated dishes and utensils, gold-plated jewelry, and chrome-plated automobile parts) <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">2. __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">electrolytic cell- __<span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';"> is an electrochemical cell used to cause a chemical change through the application on electrical energy. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">3. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">an electrolytic cell uses electrical energy (direct current) to make a nonspontaneous redox reaction proceed to completion. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">4. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">in both voltaic and electrolytic cells, electrons flow from the anode to the cathode in the external circuit. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">5. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">for both types of cells, the electrode at which reduction occurs is the cathode. The electrode at which oxidation occurs is the anode. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">6. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">The key difference between voltaic and electrolytic cells is that in a voltaic cell, the flow of electrons is the result of a spontaneous redox reaction, whereas in an electrolytic cell, electrons are pushed by an outside power source, such as a battery. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">7. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">The redox process in the voltaic cell is spontaneous; in the electrolytic cell, the redox process in nonspontaneous. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">8. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Electrolytic and voltaic cells also differ in the assignment of change to the electrodes. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">9. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">in an electrolytic cell, the cathode is considered to be the negative electrode. This is because it is connected to the negative electrode of the battery. (Remember that in a voltaic cell, the anode is the negative electrode and the cathode is the positive electrode) <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">10. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">The anode in the electrolytic cell is considered to be the positive electrode because it is connected to the positive electrode of the battery. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">B. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Electrolysis of Water <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">1. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">When a current is applied to two electrodes immersed in pure water, nothing happens. There is no current flow and no electrolysis. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">2. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">The products of the electrolysis of water are hydrogen gas and oxygen gas. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">3. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Water is reduced to hydrogen at the cathode according to the following reduction half reaction. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">4. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">The region around the cathode turns basic due to the production of OH ions. The region around the anode turns acidic due to an increase in H ions. The overall cell reaction is obtained by adding the half reactions(after doubling the first one to balance electrons) <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">C. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Electrolysis of Brine <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">1. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">If the electrolyte in an aqueous solution is more easily oxidized or reduced than water, then the products of electrolysis will be substances other than water, then the products of electrolysis will be substances other than hydrogen and oxygen. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">2. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">During electrolysis of brine, chloride ions are oxidized to produce chlorine gas at the anode. Water is reduced to produce hydrogen gas at the cathode. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">D. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Using Electrolysis in Metal Processing <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">1. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Electrolytic cells are commonly used in the plating, purifying, and refining of metals. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">2. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Many of the shiny, metallic objects you see every day – such as chrome-plated fixtures or nickel-plated coins- were manufactured with the help of electrolysis processes. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">3. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Electroplating and Electroforming <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">a. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">electroplating is the deposition of a thin layer of a metal on an object in an electrolytic cell. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">b. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">An object may be electroplated to protect the surface of the base metal from corrosion or to make it more attractive. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">c. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Many factors contribute to the quality of the metal coating that forms. In the plating solution, the concentration of the cations to be reduced must be carefully controlled. The solution must also contain compounds to control the acidity and to increase the conductivity. Other compounds may be used to make the metal coating brighter or smoother. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">d. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Electroforming is a process in which an object is reproduced by making a metal mold of it at the cathode of a cell. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">4. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Electrowinning <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">a. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">impure metals can be purified in electrolytic cells. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">b. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">The cations of molten salts or aqueous solutions are reduced at the cathode to give very pure metals. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">c. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">A common use of electrowinning is in the extraction of aluminum from its ore, bauxite. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">5. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Electrorefining <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">a. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">in this process, a piece of impure metal is made the anode of the cell <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">b. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">it is oxidized to the cation and then reduced to the pure metal at the cathode. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">c. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">This technique is used to obtain ultra pure silver, lead, and copper. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">6. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">Other Processes <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">a. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">other electrolytic processes are centered on the anode rather than the cathode. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">b. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">In electropolishing, the surface of an object at the anode is dissolved selectively to give it a high polish. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif'; mso-fareast-font-family: Tahoma; msofareastfontfamily: Tahoma; msolist: Ignore;">c. <span style="font-size: 9pt; font-family: 'Tahoma','sans-serif';">In electromachining, a piece of metal at the anode is partially dissolved until the remaining portion is an exact copy of the object at the cathode.



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