Complete the balanced dissociation equation for the compound below in aqueous solution. If the compound does not dissociate, write NR after the reaction arrow. HCLO_4(aq) →H ^+(aq)+ClO_4^−(aq).
The Correct Answer and Explanation is:
The balanced dissociation equation for perchloric acid in aqueous solution is:
[ \text{HClO}_4(aq) \rightarrow \text{H}^+(aq) + \text{ClO}_4^−(aq) ]
Explanation:
Perchloric acid (( \text{HClO}_4 )) is a strong acid. In aqueous solution, strong acids completely dissociate, meaning they separate entirely into their ions. This property makes strong acids distinct from weak acids, which only partially dissociate. When perchloric acid dissolves in water, it releases hydrogen ions (( \text{H}^+ )) and perchlorate ions (( \text{ClO}_4^- )).
Why HClO(_4) Dissociates Completely:
The dissociation strength of an acid depends on how readily it donates a proton (( \text{H}^+ )) in solution. Perchloric acid is considered one of the strongest acids because it dissociates fully in water. This complete dissociation is due to the stability of the ( \text{ClO}_4^- ) ion, which is stabilized by resonance. Resonance is a phenomenon where the negative charge is distributed evenly across all the oxygen atoms in the perchlorate ion, making it more stable. Because of this stability, the perchlorate ion is less likely to recombine with ( \text{H}^+ ), allowing for full dissociation of ( \text{HClO}_4 ).
Importance of Strong Acid Dissociation:
In aqueous solution, the dissociation of strong acids like ( \text{HClO}_4 ) contributes to the acidity by increasing the concentration of ( \text{H}^+ ) ions. This increase in ( \text{H}^+ ) ions makes the solution highly acidic. In chemical equations, this is typically represented by the products as separate ions.
Equation Verification:
Since the dissociation results in a one-to-one ratio between ( \text{H}^+ ) and ( \text{ClO}_4^- ), the equation is already balanced. No coefficients are needed, as there is one ( \text{HClO}_4 ) molecule producing one ( \text{H}^+ ) ion and one ( \text{ClO}_4^- ) ion.