Are carbonates salts?

Question

Carbonates are made from reaction between carbonic acid (or carbon dioxide) and a base (or alkali). Thus a salt is produced.

Salts are supposed to be neutral (pH7). Are metal carbonates neutral as well, or are they alkaline?

Answer 1

Carbonates are salts of the acid H2CO3 where the anion CO3 has a charge --.

As carbonic acid is a weak acid its salt from a strong base as

Na2CO3 or K2CO3 are basic

Answer 2

Yes, but because carbonic acid is so weak, sodium carbonate is also a base.

Not all salts are neutral. Only those between strong acids and strong bases are neutral, as well as those between certain weak acids and weak bases.

Do not confuse this with the term 'basic salt', which indicates that a hydroxyl group is present in the salt. Basic salts are not necessarily alkaline in pH. As a reverse example, sodium bicarbonate is an 'acidic salt' (presence of hydrogen ion), but is actually alkaline because carbonic acid is extremely weak.

Answer 3

No.  Not all salts are neutral.  Only the salts produced when a strong acid neutralizes a strong base will be neutral.

Sodium carbonate, for instance, is basic.  The final pH of the carbonate salt will depend upon the cation.