Final answer:
To determine the initial concentration of aniline in a solution with a pH of 8.79, we must calculate the pOH, determine the hydroxide ion concentration [OH-], and use the base dissociation constant (Kb) of aniline to solve for the initial concentration using an ICE table.
Step-by-step explanation:
The question is asking to calculate the initial concentration of aniline in a solution that has a pH of 8.79 at 25°C. To find the initial concentration of aniline, we need to consider the properties of aniline as a weak base and its equilibrium in an aqueous solution. The pH is related to the pOH through the relationship pH + pOH = 14 at 25°C, and the pOH is related to the hydroxide ion concentration [OH-]. We can calculate this using the equation pOH = -log[OH-]. The concentration of aniline can then be related to the [OH-] using the equilibrium constant expression for the reaction of aniline with water:
C6H5NH2 + H2O ⇌ OH- + C6H5NH3+
Using the pKa of aniline, we can find its Kb (base dissociation constant) and subsequently use an ICE table to solve for the initial concentration of aniline.
From the provided pH of 8.79, we first calculate the pOH:
Next, we calculate the concentration of hydroxide ions [OH-]:
[OH-] = 10^(-pOH) = 10^(-5.21)
Knowing the [OH-], we apply the Kb value to solve for the initial concentration of the aniline in the ICE table