CuSO (aq) + Zn (s) → Cu(s) + ZnSO (aq) ( . ) + – + – V O (s) + 5Ca (s) 2V (s) + 5CaO (s) ( . ) + – + – TiCl (l) + 2Mg (s) Ti (s) + MgCl (s) ( . ) + – + – Cr O (s) + Al (s) Al O (s) + 2Cr(s) ( .
) In each case, the reducing metal is a better reducing agent than the one that is being reduced which evidently shows more capability to lose electrons as compared to the one that is reduced. (b) Non-metal displacement: The non- metal displacement redox reactions include hydrogen displacement and a rarely occurring reaction involving oxygen displacement. All alkali metals and some alkaline earth metals (Ca, Sr, and Ba) which are very good reductants, will displace hydrogen from cold water. + – + – + 2Na(s) + 2H O(l) 2NaOH(aq) + H (g) ( .
) + – + – + Ca(s) + 2H O(l) Ca(OH) (aq) + H (g) ( . ) Less active metals such as magnesium and iron react with steam to produce dihydrogen gas: + – + – + Mg(s) + 2H O(l) Mg(OH) (s) + H (g) ( . ) + – + – 2Fe(s) + 3H O(l) Fe O (s) + 3H (g) ( . ) Many metals, including those which do not react with cold water, are capable of displacing hydrogen from acids.
Dihydrogen from acids may even be produced by such metals which do not react with steam. Cadmium and tin are the examples of such metals. A few examples for the displacement of hydrogen from acids are: + – + – Zn(s) + 2HCl(aq) → ZnCl (aq) + H (g) ( . ) + – + – Mg (s) + 2HCl (aq) → MgCl (aq) + H (g) ( .
) + – + – Fe(s) + 2HCl(aq) → FeCl (aq) + H (g) ( . ) Reactions