Question

In a redox reaction, oxidation and reduction occur simultaneously. 

(a) Write the classical concept of oxidation and reduction. 

(b) Identify the species undergoing oxidation and reduction in the following reaction: 

H₂S(S) + Cl₂ (g) → 2HCl(g) + S(s)

Answer 1

1. Oxidation: 

addition of oxygen/electronegative element to a substance or removal of hydrogen/ electropositive element from a substance.

Reduction: 

removal of oxygen/electronegative element from a substance or addition of hydrogen/ electropositive element to a substance.

2. Oxidised species: 

H₂S. This is because a more electronegative element, Cl is added to H or a more electro positive element, H has been removed from S.

Reduced species: 

Cl. This is due to addition of more electropositive element H to it.