Final answer:
An aqueous solution containing the bisulfite ion (HSO3-) at 25°C is basic because it reacts with water to produce hydroxide ions, reducing the hydronium ion concentration to less than 1 × 10^-7 M, the value for a neutral solution.
Step-by-step explanation:
An aqueous solution of HSO3- (bisulfite ion) is created at 25°C. To determine whether the solution is acidic, basic, or neutral, one has to consider the nature of the bisulfite ion in water. Bisulfite is known to react with water to form H2S (hydrogen sulfide) and hydroxide ions (OH-), which makes the solution basic. If a solution has a hydronium ion concentration [H3O+] less than 1 × 10-7 M, it is considered basic.
This implies that the bisulfite ion is providing an additional source of OH- ions, which exceeds the H3O+ ion concentration that would be present in a neutral solution (1 × 10-7 M at 25°C). Therefore, an aqueous solution of HSO3- is basic due to its ability to produce hydroxide ions when dissolved in water.