Electrochemistry Viva Questions with Answers
Question. 1. What is oxidation ?
Answer. It is a process which involves loss of electrons by a substance.
Question.2. What is reduction ?
Answer. It is a process which involves gain of electrons by a substance.
Question.3. What is a voltaic cell or electrochemical cell ?
Answer. It is a device of converting the chemical energy into electrical energy.
Question.4. Define the term emf ?
Answer. The difference of potential which causes flow of current from one electrode to another electrode in an electrochemical cell is called the electromotive force (emf).
Question.5. What is a half cell ?
Answer. It is half of the electrochemical cell where either oxidation or reduction occurs.
Question.6. Mention the names of anode and cathode of a Daniell cell ?
Answer. Zinc strip acts as anode whereas copper strip as cathode.
Question.7. Can copper be oxidised by zinc ions ?
Answer. No, zinc metal can be oxidised by Cu2+ ions.
Question.8. What is a salt bridge ?
Answer. A salt-bridge is a device to keep internal continuity between the two half cells of a voltaic cell and to prevent the physical contact between the two electrolytes. It also maintains the electrical neutrality of the electrochemical cell.
Question.9. What is the function of porous pot in a Daniell cell ?
Answer. The porous pot maintains the ionic continuity as well as prevents mixing of the two solutions.
Question.10. Name the electrolytes that can be used in salt bridge.
Answer. Potassium sulphate, potassium chloride or potassium nitrate containing agar-agar.
Question.11. What is the direction of flow of electrons in an electrochemical cell ?
Answer. Electrons move from anode to cathode in an electrochemical cell.
Question.12. What is the direction of flow of current in an electrochemical cell ?
Answer. Current flows from cathode to anode.
Question.13. What is the effect of [Zn2+] on emf of the cell Zn | Zn2+|| Cu2+ | Cu ?
Answer. The emf decreases with the increase in molar concentration of Zn2+ ions.
Question.14. What is the effect of [Cu2+] on emf of the cell Zn | Zn2+|| Cu2+ | Cu ?
Answer. The emf increases with the increase in molar concentration of Cu2+ ions.
Question.15. What is the sign of AG for the reaction in electrochemical cell ?
Answer. ∆G is – ve for the reaction in electrochemical cell.
Question.16. What factor is kept in mind while selecting an electrolytic solution for the construction of a salt bridge ?
Answer. The ions of the electrolyte in the salt should not react with ions of the electrolytes around electrodes.
Question.17. Is it possible to measure the single electrode potential ?
Answer. No, because reaction in a half cell does not take place independently.