In the reactions given below, identify the species undergoing oxidation and reduction: (i) H₂S(g) + Cl₂(g) → 2HCl(g) + S(s) (ii) 3Fe₃O₄(s) + 8Al(s) → 9Fe(s) + 4Al₂O₃(s) (iii) 2Na(s) + H₂(g) → 2NaH(s)
H₂S is oxidised; Cl₂ is reduced.
Aluminium is oxidised; Fe₃O₄ is reduced.
Sodium is oxidised; Hydrogen is reduced.
Explanation
The question requires identifying the species undergoing oxidation and reduction based on the addition/removal of electronegative elements or oxygen. In reaction (i), H₂S is oxidised as a more electronegative element (chlorine) is added to hydrogen, while chlorine is reduced due to the addition of hydrogen. In reaction (ii), aluminium is oxidised by the addition of oxygen, and Fe₃O₄ is reduced by the removal of oxygen. In reaction (iii), applying the concept of electronegativity shows that sodium is oxidised and hydrogen is reduced.