Final answer:
To find the pH of a solution of a weak base, use the equilibrium constant (Kb) and the initial concentration of the base. Set up an ICE table and use it to find the concentration of hydroxide ions using the equation Kb = [OH-][A-]/[HA]. Then, calculate the concentration of hydrogen ions ([H+]) using the pOH and find the pH.
Step-by-step explanation:
To calculate the pH of a solution of a weak base, we need to use the equilibrium constant (Kb) and the initial concentration of the base (A-).
In this case, the weak base is A- with a Kb value of 4.59 x10⁻⁷ and an initial concentration of 0.891 M. We can use an ICE table to set up a mathematical equation to find the pH.
Using the ICE table and the equation Kb = [OH-][A-]/[HA], we can calculate the concentration of hydroxide ions ([OH-]) by assuming that a small amount x of the weak base dissociates. The final equation to find x is x^2/(0.891 - x) = 4.59 x10⁻⁷.
Once we find the value of x, we can calculate the concentration of hydroxide ions in the solution, which allows us to find the pOH = -log[OH-] and then the pH. The calculated pH will be the negative logarithm of the concentration of hydrogen ions ([H+]).