Classical and Electronic Concept of Oxidation Reduction - UNSOLVED PRACTICE SET

Q7. Define oxidation and reduction according to:

(a) The classical concept

(b) The electronic concept

Q8. In the reaction: Fe₂O₃ + 3CO → 2Fe + 3CO₂, identify the species that is oxidised and the species that is reduced. Also identify the oxidising agent and the reducing agent.

Q9. Explain why the classical concept of oxidation and reduction is limited. How does the electronic concept overcome these limitations?

Q10. In the reaction: 2Mg + O₂ → 2MgO, explain the process of oxidation and reduction using both the classical and electronic concepts.

Q11. Can a substance be oxidised and reduced simultaneously in the same reaction? Explain with a suitable example.

Q12. A student claims that oxidation always involves the addition of oxygen. Is the student correct? Give an example to support your answer.

Q13. (a) Compare the classical and electronic concepts of oxidation and reduction with suitable examples.

(b) In the reaction: 2KClO₃ → 2KCl + 3O₂, identify what is oxidised and what is reduced using both concepts.

(c) Explain why the electronic concept is considered more comprehensive than the classical concept.

Q14. (a) Define oxidising agent and reducing agent according to the electronic concept.

(b) For each of the following reactions, identify the oxidising agent and the reducing agent:

(i) 2Na + Cl₂ → 2NaCl

(ii) CuO + H₂ → Cu + H₂O

(iii) 2FeCl₃ + SnCl₂ → 2FeCl₂ + SnCl₄

(iv) MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O

(c) A student argues that an oxidising agent itself gets oxidised in a redox reaction. Is the student correct? Explain with reasoning.

Q15. (a) Explain the concept of redox couples with a suitable example.

(b) Write the half-reactions for oxidation and reduction in the reaction:

Zn + CuSO₄ → ZnSO₄ + Cu

(c) In the Indian context, explain the rusting of iron (4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃) as a redox reaction, identifying what is oxidised and what is reduced using both classical and electronic concepts.

Q16. Consider the following reactions and answer the questions:

(a) 2Na(s) + Cl₂(g) → 2NaCl(s)

(b) CuO(s) + H₂(g) → Cu(s) + H₂O(g)

(c) 2Mg(s) + O₂(g) → 2MgO(s)

(d) Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

For each reaction:

(i) Identify the species oxidised and the species reduced

(ii) Identify the oxidising agent and the reducing agent

(iii) Write the electronic change (loss or gain of electrons) for the oxidised and reduced species

Q17. Analyse the following redox reactions in terms of electron transfer:

(a) 2Al + Fe₂O₃ → 2Fe + Al₂O₃ (thermite reaction used in welding railway tracks in India)

For this reaction:

(i) Write the half-reaction for oxidation

(ii) Write the half-reaction for reduction

(iii) Calculate the number of electrons transferred in the balanced equation

(iv) Identify which metal is more reactive based on this reaction

(b) 2AgNO₃ + Cu → Cu(NO₃)₂ + 2Ag

For this reaction:

(i) Identify the oxidising and reducing agents

(ii) Explain why this reaction is used in the silvering of mirrors

(iii) If 3.2 g of Cu is used, calculate the mass of Ag deposited (M of Cu = 63.5 g/mol, M of Ag = 108 g/mol)

Q18. In daily life in India, redox reactions are everywhere:

(a) When you cook food in a pressure cooker using LPG (mainly propane, C₃H₈), the combustion reaction is: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O. Identify what is oxidised and what is reduced. Explain why this is a redox reaction using the electronic concept.

(b) Photosynthesis in plants can be represented as: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Identify the oxidation and reduction processes. Which gas is produced by oxidation and which by reduction?

(c) When you charge your mobile phone, the reaction at the lithium-ion battery cathode is: LiCoO₂ ⇌ Li₁₋ₓCoO₂ + xLi⁺ + xe⁻. Explain whether charging involves oxidation or reduction at the cathode.

(d) A student notices that a copper vessel develops a green coating (verdigris, Cu₂(OH)₂CO₃) when exposed to moist air. Write the reaction and identify the redox process involved. Is this an example of corrosion? Explain.