Final answer:
To determine the unknown concentrations of all reactants and products in a 0.185 M solution of an unknown weak base, we can set up an ICE table. The ICE table will help us determine the equilibrium concentrations of the species involved. From there, we can use the equilibrium expression to calculate the unknown concentrations.
Step-by-step explanation:
To determine the unknown concentrations of all reactants and products in a 0.185 M solution of an unknown weak base, we can set up an ICE table.
In the initial row (I), we write the initial concentrations. In the change row (C), we write the change in concentrations (unknown concentrations).
In the equilibrium row (E), we write the final concentrations (known concentrations).
The ICE table for the given solution would look like:
Species Initial Concentration Change in Concentration Equilibrium ConcentrationB0.185 M-x0.185 M - xOH-0 Mxx
Using the equation for the dissociation of the unknown weak base, we can write the expression for the equilibrium constant:
Kw = [OH-] * [H+]
Since the pH is given as 12.95, we can calculate the concentration of OH- using the equation pOH = -log[OH-]. Solving for [OH-], we find [OH-] = 10^(-pOH).
Substituting the known values into the equation:
10^(-12.95) = x * (0.185 - x)
Since x is small compared to 0.185, we can approximate the equation as:
10^(-12.95) = x * 0.185
Solving for x, we find:
x = 10^(-12.95) / 0.185
Calculating this value will give us the unknown concentration of OH-. Using that value, we can then calculate the concentration of B using the equilibrium expression.