OXIDATION,REDUCTION AND ELECTROLYSIS

In the reaction 2Mg + O₂ → 2MgO, which element is oxidized? Magnesium. In the same reaction, which element is reduced? Oxygen. What is the oxidation state of oxygen in most compounds? -2. What is the oxidation state of hydrogen in most compounds? +1. What is the oxidation state of a free element like O₂ or N₂? 0. What happens to the oxidation state of an element during oxidation? It increases. What happens to the oxidation state of an element during reduction? It decreases. What is a redox reaction? A reaction in which both oxidation and reduction occur. In the reaction Zn + CuSO₄ → ZnSO₄ + Cu, which element is reduced? Copper. In the same reaction, which element is oxidized? Zinc. What type of substance donates electrons in a redox reaction? Reducing agent. What type of substance accepts electrons in a redox reaction? Oxidizing agent. What is the role of oxygen in most combustion reactions? It acts as the oxidizing agent. How can you identify the reducing agent in a redox reaction? It is the substance that loses electrons. How can you identify the oxidizing agent in a redox reaction? It is the substance that gains electrons. What is the oxidation number of chlorine in NaCl? -1. What is the oxidation number of sulfur in H₂SO₄? +6. What is the oxidation number of nitrogen in NH₃? -3. What is the oxidation number of carbon in CO₂? +4. Why are redox reactions important in biological systems? They are involved in processes like cellular respiration and photosynthesis. What happens to the electrons during a redox reaction? They are transferred from one species to another. How does the oxidation state of an atom change in a reducing agent? It increases. What is the primary characteristic of a disproportionation reaction? The same element is simultaneously oxidized and reduced. What is an example of a disproportionation reaction? 2H₂O₂ → 2H₂O + O₂. What is the purpose of a salt bridge in an electrochemical cell? It maintains electrical neutrality by allowing ion flow. What happens at the anode of an electrochemical cell? Oxidation. What happens at the cathode of an electrochemical cell? Reduction. Which type of redox reaction occurs in batteries to generate electrical energy? Spontaneous redox reactions. Which describes the oxidizing agent in a chemical reaction? the substance that is reduced because it gains electrons Given the reaction below, which is the oxidized substance? Mg + Cl2 Mg2+ + 2Cl Mg Which best identifies why the rusting of an iron nail in the presence of water and oxygen is an oxidation-reduction reaction? Electrons are transferred. Which type of reaction occurs in the following? 2HgO(s) 2Hg(l) + O2(g) a decomposition reaction in which a metal is reduced Given the reaction below, which is the reduced substance?Mg + Cl2 Mg2+ + 2Cl CI2 Which best describes the oxidizing agent in this reaction? Cl2(aq) + 2Br(aq) 2Cl(aq) + Br2(aq) Chlorine (Cl) is the oxidizing agent because it gains an electron. Consider the following reaction. CO2(g)+H2(g)--->CO(g)+H2O(l) What is being oxidized? Hydrogen What is the oxidation number for S in the compound SO3? (Recall that O has an oxidation number of -2.) +6 Which of the following is a simple definition of oxidation? the loss of electrons Which of the following is true about a redox reaction? In a redox reaction, an electron is lost by the reducing agent. The presence of which reactant is the best indicator of an oxidation-reduction reaction? H2 Which answer best describes what is happening in the following reaction? This is a redox reaction in which octane (C8H18) is oxidized. In the reaction equation BrO-3(aq) Br-(aq) + BrO-4(aq), how many oxidation states does the disproportionate substance have throughout the reaction? D Which of these describes the oxidation number of oxygen during this reaction? C Which identifies an oxidation-reduction reaction? C Given the reaction below, which is the reduced substance?Mg + Cl2 --> Mg2+ + 2Cl- Cl2 Which of the following is an oxidation-reduction reaction? ZnS(s) + 2O2(g) ---> ZnSO4(s) Half-reaction A chemical equation explicitly showing either oxidation or reduction Half-reaction method Procedure that involves writing separate, balanced equations for the oxidation and reduction processes called half-reactions Oxidation a process that involves complete or partial loss of electrons or a gain of oxygen Oxidizing agent The electron acceptor in a redox reaction. Oxidation number a positive or negative number assigned to an atom to indicate its degree of oxidation or reduction Oxidation number-change method a method of balancing a redox equation by comparing the increases and decreases in oxidation number. Oxidation-reduction reaction a reaction that involves the transfer of electrons between reactants, Redox reaction A chemical reaction involving the transfer of one or more electrons from one reactant to another; also called oxidation-reduction reaction. Reduction a process that involves a complete or partial gain of electrons or the loss of oxygen Reducing agent substance in a redox reaction that donates electrons, the reducing agent is oxidized Molten salts are electrolyzed to produce their constituent elements by breaking the ionic bonds using electric current. Explain the electrolysis of molten sodium chloride. Molten sodium chloride is electrolyzed to produce sodium metal at the cathode and chlorine gas at the anode. Write the half-reactions for the electrolysis of molten sodium chloride. At the cathode: Na+ + e⁻ → Na At the anode: 2Cl⁻ → Cl₂ + 2e⁻ What safety precautions are necessary during electrolysis? Wear protective gear, handle chemicals with care, and ensure proper ventilation to avoid exposure to harmful gases. How is electrolysis used in hydrogen production? Electrolysis of water is a method to produce hydrogen gas, which can be used as a clean energy source. What factors affect the rate of electrolysis? The rate depends on the current, voltage, concentration of the electrolyte, and temperature. What is the industrial importance of electrolysis? Electrolysis is used in the production of metals, chemical synthesis, electroplating, and energy storage systems like batteries. How are reactive and non-reactive electrodes different in electrolysis? Reactive electrodes participate in the reaction, while non-reactive electrodes, like platinum, only serve as conductors. What gases are evolved during the electrolysis of brine? Chlorine gas is evolved at the anode, and hydrogen gas is evolved at the cathode. Write the chemical equation for the electrolysis of brine. 2NaCl(aq) + 2H₂O(l) → Cl₂(g) + H₂(g) + 2NaOH(aq) What is the role of inert electrodes in electrolysis? Inert electrodes, like graphite or platinum, do not react with the electrolyte or products and are used to conduct electricity.