What are the concentrations of all the solute species in a 1.2 M solution of acetic acid, HC2H3O2?
(a) [H3O+], M;
(b) [OH-], M;
(c) [CH3COOH], M;
(d) What is the pH of the solution? For CH3COOH, Ka = 1.8 x 10-5
You want the ionization and Ka. To make things simple for typing, we will call acetic acid HAc.
HAc + H2O ==> H3O + Ac^-
Ka = (H3O^+)(Ac^-)/(HAc)
Set up an ICE chart, substitute into Ka expression and solve for H3O^+, Ac^-, and HAc. For OH, use (H^+)(OH^-) = 1 x 10^-14; OH can be calculated knowing H^+.
To determine the concentrations of the solute species in a 1.2 M solution of acetic acid, HC2H3O2, we need to consider the dissociation reaction of acetic acid:
CH3COOH ⇌ H3O+ + CH3COO-
From the equation, we can see that acetic acid (CH3COOH) dissociates into hydrogen ions (H3O+) and acetate ions (CH3COO-).
(a) The concentration of H3O+ is equal to the concentration of H3O+ formed from the dissociation of acetic acid. Therefore, the concentration of H3O+ is equal to the initial concentration of acetic acid since acetic acid is a weak acid and only partially ionizes. Therefore, the concentration of H3O+ in this solution is 1.2 M.
(b) Acetic acid is a weak acid, which means it only ionizes partially. The concentration of OH- ions in a solution of acetic acid is determined by the autoionization of water. Since acetic acid does not directly produce OH- ions, the concentration of OH- in this solution is determined by the autoionization of water, which is 1 x 10^-14 M at 25°C.
(c) The concentration of CH3COOH is given as 1.2 M, which is the initial concentration of acetic acid in the solution.
(d) To calculate the pH of the solution, we need to use the equation:
pH = -log[H3O+]
Using the concentration of H3O+ (1.2 M), we can calculate the pH using a calculator or the logarithmic function of a scientific calculator. In this case, the pH of the solution is equal to -log(1.2) = -0.08.
Therefore, the concentrations of the solute species in the 1.2 M solution of acetic acid are:
(a) [H3O+] = 1.2 M;
(b) [OH-] = 1 x 10^-14 M;
(c) [CH3COOH] = 1.2 M;
(d) The pH of the solution is -0.08.