(a) Why do acids not show acidic behaviour in the absence of water?
(b) Why does an aqueous solution of an acid conduct electricity?
(c) Why does distilled water not conduct electricity whereas rainwater does?
(a) The acidic behavior of an acid is due to the presence of hydrogen ions [H+(aq) ions] which are produced only when acids are dissolved in water. In the absence of water, acids do not produce hydrogen ions and hence do not show acidic behavior.
(b) The aqueous solution of an acid conducts electricity due to the presence of charged particles called ‘ions’ in it. These ions carry electric current.
(c) Distilled water does not conduct electricity because it does not contain any ionic compounds dissolved in it whereas rain water does.
Reason: When rain water falls on earth through the atmosphere, it dissolves an acidic gas ‘carbon dioxide’ from the air and forms carbonic acid (H2CO3). The carbonic acid provides some hydrogen and carbonate ions to the rain water. Due to the presence of these ions, rain water conducts electricity.