Determine the percent ionization of a 2.45 M solution of benzoic acid
Let HBz be bezoic acid
..........HBz ==> H^+ + Bz^-
I.........2.45....0......0
C..........-x.....x......x
E.......2.45-x....x......x
Substitute the E line into Ka for HBz (you will need to look that up in your text/notes) and solve for x
Then %ionization = [(H^+)/2.45]*100 = ?
To determine the percent ionization of a solution, you need to know the initial concentration of the acid and the concentration of the ionized form. In this case, you are given the initial concentration of the benzoic acid solution, but you need additional information on the degree of ionization of benzoic acid at that concentration.
The degree of ionization can vary based on factors such as temperature and acid strength. Benzoic acid is a weak acid, meaning it does not completely ionize in water. The degree of ionization can be determined by calculating the acid dissociation constant (Ka) for benzoic acid.
The Ka value for benzoic acid is 6.3 x 10^-5 at 25°C. The Ka value represents the ratio of the concentrations of the ionized form to the unionized form at equilibrium. Since benzoic acid is a monoprotic acid, it dissociates into one hydrogen ion (H+) and one benzoate ion (C6H5COO-) in water.
To calculate the percent ionization, you need to determine the concentration of the ionized form. Let's assume the degree of ionization is x.
The ionized form (C6H5COO-) would be x M, and the unionized form (C6H5COOH) would be (initial concentration - x) M. Since the initial concentration of benzoic acid is 2.45 M, the concentration of the ionized form would be (2.45 - x) M.
Using the Ka expression for benzoic acid:
Ka = [C6H5COO-][H+] / [C6H5COOH]
Substituting the known values:
6.3 x 10^-5 = x * x / (2.45 - x)
Solving the equation to find the value of x gives the degree of ionization for benzoic acid at that concentration. Substitute this value into the equation below to find the percent ionization:
Percent Ionization = (Concentration of the ionized form / Initial concentration) * 100
By following these steps and performing the calculations, you can determine the percent ionization of the given 2.45 M solution of benzoic acid.