Answer:
The weak base is hydroxylamine
Explanation:
The general equilibrium of a weak base (A), is:
A(aq) + H₂O(l) ⇄ HA⁺ + OH⁻
Where Kb is:
Kb = [HA⁺] [OH⁻] / [A]
As both HA⁺ and OH⁻ comes from the equilibrium of A; HA⁺ = OH⁻. So, you can take:
Kb = [OH⁻]² / [A]
OH⁻ is determined from pH, thus:
pOH = -log [OH⁻]
pOH = 14 - pH
pOH = 14 - 9.44
pOH = 4.56
[OH⁻] = 10^{-4.56}
[OH⁻] = 2.75x10⁻⁵
As the concentration of the weak base is 0.0678M:
Kb = [OH⁻]² / [A]
Kb = [2.75x10⁻⁵]² / [0.0678M]
Kb = 1.1x10⁻⁸ = Kb of Hydroxylamine.
