How do buffer solutions work

Clearly each buffer will work in a specific way to maintain the pH of 

These consist of a weak acid and a salt of that acid. 

Ethanoic acid is only partially dissociated into ions  

Sodium ethanoate is an ionic compound it is completely dissociated 

In the laboratory and in industry there is a need for buffer solutions to maintain the alkalinity of systems. An alkaline buffer solution is a mixture of a weak alkali and its salt, such as a solution of aqueous ammonia with ammonium chloride. Ammonia in water is partially protonated (3) and its salt is fully dissociated (4). Alkaline buffer solutions work in a similar way to acidic ones to keep the pH of a system above 1. 

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