How can you determine if NH4ClO2 is an acid, base, or neutral using Ka and Kb values?
The correct answer and explanation is:
To determine if NH4ClO2 is an acid, base, or neutral, we can look at the dissociation constants, Ka (acid dissociation constant) and Kb (base dissociation constant), for its components.
- NH4+ (Ammonium ion): Ammonium (NH4+) is the conjugate acid of ammonia (NH3). It tends to release a proton (H+) when it dissociates in water. The strength of this acid can be assessed using its Ka value. Ammonium has a Ka value around 5.6 × 10^-10, which is relatively small, indicating that NH4+ is a weak acid. It does not dissociate completely in water.
- ClO2- (Chlorite ion): Chlorite (ClO2-) is the conjugate base of chlorous acid (HClO2). The strength of this base can be assessed using its Kb value. The Kb for ClO2- is relatively large (around 2.2 × 10^-8), indicating that it is a weak base. This means ClO2- has a tendency to accept a proton and increase the pH of the solution.
Now, let’s combine the information from NH4+ and ClO2-. When dissolved in water, NH4ClO2 will dissociate into NH4+ and ClO2-. Because NH4+ is a weak acid and ClO2- is a weak base, the overall behavior of the solution depends on the relative strengths of these two ions.
To determine whether the solution is acidic, basic, or neutral, we can compare the Ka of NH4+ and the Kb of ClO2-. If Ka > Kb, the solution will be acidic. If Ka < Kb, the solution will be basic. If Ka = Kb, the solution will be neutral.
In this case, NH4+ is a stronger acid than ClO2- is a base (since Ka > Kb), meaning that NH4ClO2 will produce an acidic solution when dissolved in water. Therefore, NH4ClO2 behaves as an acid in aqueous solution.