Do metal carbonates such as $C a C O_{3}$ , $N a_{2} C O_{3}$ etc are acidic in nature or basic?

Answer

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Hint: We know that an acid is a species which accepts an electron pair whereas a base is a species which has a tendency to donate an electron pair in a chemical reaction. The acidic and basic nature can be explained in terms of proton transfer as well, i.e.; an acid is a proton donor while a base is a proton acceptor.

Complete answer:
Carbonates which are prepared by the reaction of carbon dioxide with metal oxides and metal hydroxides, are moderately strong bases and their aqueous solutions are also basic because the carbonate anion has a tendency to accept a hydrogen ion from water molecule as per following reaction:

C O_{3}^{2 -} + H_{2} O \to H C O_{3}^{-} + O H^{-}

Carbonates, specifically metal carbonates react with acids to form the salts of metal along with the removal of gaseous carbon dioxide and water. The real life example for this reaction is an antacid which consists of active ingredients of calcium carbonate with the acid present in our stomach i.e., hydrochloric acid to neutralise the acid effect. The reaction takes place as follows:

C a C O_{3} + 2 H C l \to C a C l_{2} + C O_{2} + H_{2} O

Thus, we can conclude that the metal carbonates such as

C a C O_{3}

N a_{2} C O_{3}

are basic in nature.

Note:
Remember that metal bicarbonates are amphoteric i.e., can behave as both acid and base but their aqueous solutions are weakly alkaline due to the formation of carbonic acid and hydroxide ion whereas in case of metal carbonates, they are basic in nature and their aqueous solutions are strongly alkaline.