question_answer

Why is it that on being heated in excess supply of air, K, Rb and Cs form super oxides in preference to oxides and peroxides?

Answer:

                \[{{K}^{+}},\,R{{b}^{+}}\] and \[C{{s}^{+}}\] are large cations and superoxide ion \[(O_{2}^{-})\] is larger than oxide \[({{O}^{2-}})\] and peroxide \[(O_{2}^{2-})\]ions. Since a large cation stabilizes a large anion, therefore, these metals form super oxides in preference to oxides and peroxides.