Chemistry 2nd Ch 04 Electrochemistry

Chemistry - Second Paper Chapter 4 : Electrochemistry HSC 2028 - English Version Creative Questions A. Knowledge Based Questions 1. What is electrode? [D.B.16] Answer: An electrode is a solid electrical conductor through which electric current enters or leaves an electrochemical cell or other medium. 2. What is salt bridge? [D.B.16] Answer: A salt bridge is a U-shaped tube containing an inert electrolyte (like KCl or KNO3) in an agar-agar gel, used to connect the oxidation and reduction half-cells of a galvanic cell to maintain electrical neutrality. 3. What is called oxidation potential? Answer: The tendency of an electrode to lose electrons when placed in a solution of its own ions is called its oxidation potential. 4. What is electrochemical equivalent? Answer: Electrochemical equivalent is de ned as the mass of a substance deposited or liberated at an electrode when a steady current of one ampere is passed for one second (i.e., one coulomb of charge). 5. What is electrolysis? Answer: Electrolysis is the process in which an electric current is passed through an electrolyte in molten or aqueous state, causing a non-spontaneous chemical change (decomposition). 6. What are electr

B. Understanding Based Questions 1. Reduction potential of Zn is −0.76 V. What do you mean by this? [R.B.16] Answer: The standard reduction potential of Zn is −0.76 V means that when a zinc half-cell is coupled with a standard hydrogen electrode (SHE) under standard conditions, zinc has a lesser tendency to gain electrons than H+. Instead, Zn oxidizes spontaneously, making it the anode, and the cell potential is 0.76 V. 2. What do you mean by the electrochemical equivalent of silver is 1.118 × 10−3 g C−1? [J.B.16] Answer: It means that when 1 Coulomb of electric charge (1 Ampere current for 1 second) is passed through an aqueous solution containing silver ions (e.g., AgNO3), exactly 1.118 × 10−3 grams of silver metal is deposited at the cathode. 3. Galvanic cell gives redox reaction. Explain. [Co.B.16] Answer: In a galvanic cell, a spontaneous redox reaction generates electricity. Oxidation (loss of electrons) occurs at the anode, while reduction (gain of electrons) occurs at the cathode. The electrons travel through an external circuit from anode to cathode, driving the overall chemical reaction while doing electrical work. 4. Write down the dierences between electrolytic cell

provide a higher voltage (around 3.6 V) compared to other rechargeable cells, making them ideal for portable electronics. 10. Explain the in uence of concentration and temperature on electrode potential. Answer: According to the Nernst equation (E = E◦−(RT/nF) ln Q), the electrode potential depends on both temperature (T) and concentration (Q). An increase in temperature or a decrease in reactant concentration typically lowers the reduction potential. Standard potentials (E◦) are speci cally de ned at 298 K and 1 M concentration. 11. Explain why aqueous NaCl is a conductor. Answer: In aqueous solution, the ionic bonds in solid NaCl are broken by hydration, dissociating the salt into freely moving Na+ and Cl ions. When a potential dierence is applied, these mobile ions migrate towards oppositely charged electrodes, thereby carrying and conducting electric current through the solution. 12. Electrolysis is a redox reaction - Explain. [HSC18] Answer: During electrolysis, electrical energy forces a chemical reaction to occur. At the cathode, cations gain electrons and are reduced. At the anode, anions (or the anode material itself) lose electrons and are oxidized. Because oxidation a