Almost all metals combine with oxygen to form metal oxides. Metal oxides are generally basic in nature. But…
Almost all metals combine with oxygen to form metal oxides. Metal oxides are generally basic in nature. But some metal oxides show both basic as well as acidic behaviour. Different metals show different reactivities towards oxygen. Some react vigorously while some do not react at all.
(a) What happens when copper is heated in air ? (Give the equation of the reaction involved).
(b) Why are some metal oxides categorized as amphoteric ? Give one example.
(c) Complete the following equations :
(i) Na2O(s) + H2O(l) →
(ii) Al2O3 + 2 NaOH →
Solution
(a) 2Cu + O2 → 2CuO
(b) Because they react with both acids and bases to produce salt and water.
Al2O3/ ZnO (any one)
(c) (i) Na2O(s) + H2O(l) → 2NaOH(aq)
(ii) Al2O3 + 2NaOH → 2NaAlO2 + H2O