18-1 . Bricfly describe or define (a) oxidation. (b) reducing agent. (c) salt bridge. (d) liquid junction. (c) Nernst equation. 18-2 . Bricfly describe or define (a) electrode potential. (b) formal potential. (c) standard electrode potential. (d) liquid-junction potential. (c) oxidation potential. 18-3. Make a clear distinction between (a) oxidation and oxidizing agent. (b) an electrolytic cell and a galvanic cell. (c) the cathode of an electrochen nical cell and the right-hand electrode. (d) a reversible electrochemical cell and an irrevers- ible electrochemical cell. (c)the standard electrode potential and formal potential.

18-1. Briefly describe or define:<br />(a) Oxidation: Oxidation is a chemical reaction in which a substance loses electrons. This process is often accompanied by an increase in the oxidation state of the substance. Oxidation can occur in various types of reactions, such as combustion, rusting, and redox reactions.<br /><br />(b) Reducing agent: A reducing agent is a substance that donates electrons to another substance during a chemical reaction. By donating electrons, the reducing agent reduces the oxidation state of the other substance. In other words, it causes the other substance to be reduced.<br /><br />(c) Salt bridge: A salt bridge is a device used in electrochemical cells to maintain electrical neutrality. It consists of a tube filled with a salt solution, which allows ions to move between the two half-cells. The movement of ions through the salt bridge helps to balance the charge as electrons flow through the external circuit.<br /><br />(d) Liquid junction: A liquid junction is the interface between two solutions with different concentrations of ions. When these solutions are connected, ions can migrate from one solution to the other, creating a potential difference known as the liquid-junction potential.<br /><br />(e) Nernst equation: The Nernst equation is a mathematical relationship that describes the relationship between the cell potential (electrochemical potential) and the concentration of reactants in an electrochemical cell. It takes into account the standard electrode potential, the reaction quotient, and the temperature to calculate the cell potential under non-standard conditions.<br /><br />18-2. Briefly describe or define:<br />(a) Electrode potential: Electrode potential, also known as cell potential or electromotive force (EMF), is the measure of the potential difference between two electrodes in an electrochemical cell. It is the driving force that causes electrons to flow from one electrode to the other during a redox reaction.<br /><br />(b) Formal potential: Formal potential, also known as standard electrode potential, is the potential of an electrode under standard conditions. It is a measure of the tendency of a substance to gain or lose electrons and is typically measured in volts (V).<br /><br />(c) Standard electrode potential: Standard electrode potential is the potential of an electrode when all reactants and products are at their standard concentrations (usually 1 M) and the temperature is at standard conditions (usually 25°C). It is a measure of the tendency of a substance to gain or lose electrons under standard conditions.<br /><br />(d) Liquid-junction potential: Liquid-junction potential is the potential difference that arises when two solutions of different concentrations are connected by a salt bridge. This potential difference is caused by the migration of ions between the two solutions and is typically measured in volts (V).<br /><br />(e) Oxidation potential: Oxidation potential, also known as oxidation state, is the measure of the tendency of a substance to be oxidized (lose electrons). It is typically represented by a numerical value and is used to predict the feasibility of redox reactions.<br /><br />18-3. Make a clear distinction between:<br />(a) Oxidation and oxidizing agent: Oxidation is a chemical reaction in which a substance loses electrons, resulting in an increase in its oxidation state. On the other hand, an oxidizing agent is a substance that gains electrons during a chemical reaction. It causes the oxidation of another substance by accepting electrons from it.<br /><br />(b) An electrolytic cell and a galvanic cell: An electrolytic cell is an electrochemical cell in which an external source of electrical energy is used to drive a non-spontaneous redox reaction. In contrast, a galvanic cell electrochemical cell in which a spontaneous redox reaction occurs, and electrical energy is generated.<br /><br />(c) The cathode of an electrochemical cell and the right-hand electrode: The cathode is the electrode in an electrochemical cell where reduction occurs. It is the site where electrons are gained by the species undergoing reduction. The right-hand electrode is not a standard term used in electrochemistry.<br /><br />(d) A reversible cell and an irreversible electrochemical cell: A reversible electrochemical cell is one in which the redox reaction can proceed in both directions, allowing for the regeneration of the reactants. In contrast, an irreversible electrochemical cell is one in which the redox reaction proceeds in only one direction, and the reactants cannot be regenerated.<br /><br />(e) The standard electrode potential and formal potential: The standard electrode potential is the potential of an electrode under standard conditions, which is a measure of the tendency of a substance to gain or lose electrons under standard conditions. The formal potential, also known as the Nernst equation, takes into account the non-standard conditions and the reaction quotient to calculate the cell potential.