Example 4.4: Writing Equations for Acid-Base Reactions
Write balanced chemical equations for the acid-base reactions described here:
(a) the weak acid hydrogen hypochlorite reacts with water
(b) a solution of barium hydroxide is neutralized with a solution of nitric acid
Solution
(a) The two reactants are provided,
\(\ce{HOCl}\) and
\(\ce{H2O}\). Since the substance is reported to be an acid, its reaction with water will involve the transfer of
\(\ce{H+}\) from
\(\ce{HOCl}\) to
\(\ce{H2O}\) to generate hydronium ions,
\(\ce{H3O+}\) and hypochlorite ions,
\(\ce{OCl-}\).
\(\ce{HOCl(aq)}\)\(\ce{ + }\)\(\ce{H2O(l)}\)\(\ce{<=>}\)\(\ce{OCl-(aq)}\)\(\ce{ + }\)\(\ce{H3O+(aq)}\)\(\ce{ }\)
A double-arrow is appropriate in this equation because it indicates the
\(\ce{HOCl}\) is a weak acid that has not reacted completely.
(b) The two reactants are provided,
\(\ce{Ba(OH)2}\) and
\(\ce{HNO3}\). Since this is a neutralization reaction, the two products will be water and a salt composed of the cation of the ionic hydroxide
\(\ce{(Ba^2+)}\) and the anion generated when the acid transfers its hydrogen ion (
\(\ce{NO3-}\) ).
\(\ce{Ba(OH)2(aq)}\)\(\ce{ + }\)\(\ce{2HNO3(aq)}\)\(\ce{->}\)\(\ce{Ba(NO3)2(aq)}\)\(\ce{ + }\)\(\ce{2H2O(l)}\)\(\ce{ }\)