ELECTROCHEMISTRY.pptx used in daily life
- 2. WHAT IS ELECTROCHEMISTRY • Electrochemistry is the study of the generation of electricity from the energy released during spontaneous chemical reactions as well as application of electrical energy to non spontaneous chemical reactions. • Electrochemistry is the study of chemical processes that cause electrons to move. • Electrochemistry deals with oxidation-reduction reactions that either produce or utilize electrical energy.
- 3. Electrolytic Cell electrical energy produces a chemical change. Reversible cell Galvanic Cell / Daniel cell / Electrochemical cell chemical energy to electrical energy conversion Irreversible cell Electrolysis is the breakdown of a compound into its constituent parts using an electric current. A compound that is either molten or in the solution can undergo electrolysis, which is a chemical transformation. Cell Types
- 4. ELECTROLYTIC CELL Components of Electrolytic Cell 1. Electrolyte: The electrolyte, which is the substance that breaks down in the electrolysis cell, can either be a molten ionic compound or a concentrated aqueous solution of ions. 2. Electrodes: The electrodes, which are rods made of metal or carbon (graphite), conduct electricity to and from the electrolyte. • Anode: The positive electrode • Cathode: The negative electrode 3. Direct current: The power supply must be direct current. Redox reactions in electrolysis Molten sodium chloride (NaCl) can be subjected to electrolysis with the help of an electrolytic cell, as illustrated below.
- 5. There, two inert electrodes are dipped into molten sodium chloride (which contains dissociated Na+ cations and Cl– anions). When an electric current is passed into the circuit, the cathode becomes rich in electrons and develops a negative charge. The positively charged sodium cations are now attracted towards the negatively charged cathode. This results in the formation of metallic sodium at the cathode. Simultaneously, the chlorine atoms are attracted to the positively charged cathode. This results in the formation of chlorine gas (Cl2) at the anode (which is accompanied by the liberation of 2 electrons, finishing the circuit). At cathode: Reduction occurs 2Na(l)+ + e– → Na(l) At anode: Oxidation occurs 2Cl–(l) → Cl2(g) + 2e– Net reaction is written as: 2Na +(l) + 2Cl–(l) → 2Na(l) + Cl2(g)
- 6. The Gibbs free energy of a system decreases during a spontaneous chemical reaction. In electrochemistry, redox reactions that occur spontaneously transform chemical energy into electrical energy. A non-spontaneous chemical reaction can also happen oppositely by applying electricity. An electrochemical cell is a device or apparatus that generates electric current from chemical change. An electric current is created when electrons are transferred from one chemical species to another. ELECTROCHEMICAL CELL
- 7. Components of Electrochemical Cells The main components of an electrochemical cell are: 1. Electrodes – The solid electrical conductors found in electrochemical cells made of good conductors like metals. They are of two categories: a. The Anode – The cell compartment in which oxidation occurs. b. The Cathode- The cell compartment where reduction occurs. 2. Electrolyte: The term “electrolyte” refers to a substance that lies between the electrodes and, when dissolved in polar solvents like water, produces freely moving ions that form an electrically conducting solution. 3. External Circuit: The external circuit enables the movement of electrons from the anode to the cathode. This spontaneous flow can generate energy that can produce heat or perform work in the case of a galvanic cell. This needs an energy source to function in the case of an electrolytic cell. 4. Salt Bridge: An electrochemical cell’s oxidation and reduction halves are connected by a salt bridge, completing the circuit. It is stuffed full of KCl and other saturated salt solutions. The bridge is necessary for the solution’s ions to move between half-cells, which is necessary for the reaction to proceed. An illustration of a salt bridge is filter paper dip in potassium nitrate or sodium chloride solution.
- 8. Working of a Electrochemical cell Electric work done by a galvanic cell is mainly due to the Gibbs energy of spontaneous redox reaction in the voltaic cell. It generally consists of two half cells and a salt bridge. Each half cell further consists of a metallic electrode dipped into an electrolyte. These two half-cells are connected to a voltmeter and a switch externally with the help of metallic wires. In some cases, when both the electrodes are dipped in the same electrolyte, a salt bridge is not required. Daniel’s cell is an example of a galvanic cell that converts chemical energy into electrical energy. In Daniel’s cell, copper ions are reduced at the cathode while zinc is oxidized at the anode. Reactions of Daniel cell at cathode and anode are: At cathode: Cu 2+ + 2e– Cu → At anode: Zn Zn → 2+ + 2e–
- 10. Why do we need a salt bridge ? A salt bridge is a U-shaped tube filled with an electrolyte solution that connects the oxidation and reduction half-cells of a galvanic cell. The main function of a salt bridge is to help maintain electrical neutrality within the internal circuit. It also helps in preventing the cell from taking its reaction to equilibrium. If salt bridges are absent or if they are not used, then the reaction will likely continue, and the solution in one-half electrodes will gather a negative charge. Similarly, in the other half, electrodes will accumulate a positive charge. This will further result in the stoppage of the reaction, and no electricity will be produced.
- 11. APPLICATIONS OF ELECTROCHEMISTRY 1. ELECTROPLATING Electroplating is basically the process of plating a metal onto the other by electrolysis mostly to prevent corrosion of metal or for decorative purposes. To understand the concept further, let’s take an example of a gold coating. In this instance, a layer of gold is to be electrodeposited on metallic spoon to enhance its appearance. Preparing the Surface The purpose of preparing the surface before beginning to plate another metal onto it is to ensure that it is clean and free of contaminants, which may interfere with the bonding. Contamination often prevents deposition and lack of adhesion
- 12. At cathode: Reduction occurs Au2+ + e– → Au At anode: Oxidation occurs Au → Au2+ + e– The process Usually, the gold plating is connected to the anode (+ve charged electrode) of the circuit and the spoon is kept at the cathode (-ve charged electrode). Both are kept immersed in a highly developed electrolytic bath (solution). At this stage, a DC current is supplied to the anode that oxidizes the gold atoms and dissolves them into the solution. The dissolved ions of gold are reduced at the cathode and plated on the spoon.
- 13. Uses of Electroplating The major application is to optimize a material’s resistance towards corrosion. The plated layer often serves as a sacrificial coating which reveals that it dissolves before the base substance. Improving wear resistance(Wear resistance is a material's ability to resist the loss of material from its surface due to mechanical actions like sliding, rubbing, or scraping) Improving the thickness of the metal surface. Enhancing the electrical conductivity like plating a copper layer on an electrical component. Improving surface uniformity. Importance of electroplating in day to day life Starting from household cutlery, to automobile parts to the jewelry that we use in our daily lives every thing uses the concept of electroplating. In electroplating metals such as Zinc, Copper, Tin, Chromium, Gold, Nickel, Silver, and Palladium are electroplated on the objects. If I discuss in detail regard the utilities:
- 14. 1. Copper : Kitchenware: Pots, pans, sink taps are electroplated to help them last longer and maintain their appearance. Currency: Copper electroplating is used for minting money(Minting money is the process of producing coins, or making money out of metal) 2. Nickel plating : Machineries: bumpers, exhaust pipes, bicycles, and motorcycles Electronics: used for microprocessors, connectors, integrated circuits, and contacts to ensure functionality and reliability. Aerospace industry: Electroplating is widely used in the aerospace industry to protect components such as landing gear and engine parts from corrosion. BUMPERS MICROPROCESSO R LANDING GEAR
- 15. 5. Zinc – Construction: Steel beams Military: Armored tanks, personnel carriers, heavy vehicles Food and beverage: Food cans 6. Chromium – Bathroom and kitchen fixtures: Showers, bath taps, and gas burners STEEL BEAMS ARMORED TANKS Hence we can confidently say that the electroplating plays a very major role in our daily lives
- 16. 2. ELECTROREFINIG Electrolytic Refining of Copper Electrorefining is a process that uses electrolysis to purify materials, usually metals, in an electrolytic cell. Here, we will take an example of electrolytic copper refining to understand the process more clearly. Copper is usually mined from coal, known as blister copper. It is about 98 to 99 per cent pure. However, the electro-refining process can easily make it 99.95% pure, which makes it a good product to be used in electrical components. A block of impure copper is taken as an anode or positive electrode. Copper sulfate, which is acidified with sulphuric acid, is used as electrolyte, along with pure copper tubes, as a cathode or negative electrode. In this phase of electrolysis, copper sulfate divides into a positive ion of copper (Cu2+) and a negative ion of sulfate (SO42—). The positive copper ion (Cu2+) or cations travel towards the negative electrode made of pure copper, where it absorbs the electrons from the cathode. Cu atom is deposited on the cathode’s graphite layer. However, the anode’s metallic impurities are also mixed with SO42-, forming metallic sulfate in the electrolyte solution and dissolving and getting settled down as the anode sludge or dust.
- 17. At cathode: Reduction occurs Cu2+ + 2e– → Cu At anode: Oxidation occurs Cu → Cu2+ + 2e– By this way we get pure metal from its impure compounds.
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