Question

enough of a monoprotic acid is dissolved in water to produce a 1.64 m solution. the ph of the resulting solution is 2.95 . calculate the ka for the acid.

Answer 1

To find the acid dissociation constant (Ka) for the acid, calculate the concentration of hydrogen ions from the pH, then apply the dissociation reaction to find the equilibrium concentrations and solve for Ka.

Step-by-step explanation:

To calculate the acid dissociation constant (Ka) for the acid, we can use the information provided about the solution's molarity and pH. First, we translate the pH to a concentration of hydrogen ions: [H+] = 10-pH = 10-2.95.

For a monoprotic acid HA dissolving in water, the dissociation is represented as:

HA(aq) + H2O(l) ⇌ H+(aq) + A-(aq).

At equilibrium, the dissociation of the acid will have produced an equal amount of H+ and A-, so the concentration of A- will be the same as the concentration of hydrogen ions [A-] = [H+].

The initial concentration of the acid [HA]initial is given as 1.64M, so the concentration of undissoicated acid will be [HA] = [HA]initial - [H+].

The acid dissociation constant Ka can be represented as:

Ka = ×× [H+] [H+](A-)/[HA]

Substituting the known quantities and solving for Ka:

Ka = [H+]^2 / ([HA]initial - [H+])

Calculating Ka, we take [H+] = 10-2.95 and [HA]initial = 1.64 M.

From this, you can derive the value of Ka that characterizes the acid's strength.

Answer 2

To calculate the Ka for the acid in the given solution, you can use the equation pH = -log[H3O+] to find the concentration of H3O+ ions in the solution. Since the acid is monoprotic, the concentration of the acid is equal to the concentration of H3O+ ions. This concentration can be used to calculate the Ka using the equation Ka = [H3O+][A-] / [HA].

Step-by-step explanation:

The Ka (acid dissociation constant) measures the degree of ionization of a weak acid in water. To calculate the Ka for the acid in the given solution:

1. Use the equation pH = -log[H3O+] to find the concentration of H3O+ ions in the solution. In this case, pH = 2.95, so [H3O+] = 10⁻²·⁹⁵.
2. Since the acid is monoprotic (meaning it donates only one hydrogen ion), the concentration of the acid is equal to the concentration of H3O+ ions. Therefore, the concentration of the acid is 10⁻².⁹⁵ M.
3. The Ka can be calculated using the equation Ka = [H3O+][A-] / [HA], where [H3O+] is the concentration of the acid, [A-] is the concentration of the conjugate base, and [HA] is the initial concentration of the acid.

Plugging in the values, the Ka for the acid is calculated to be 3.88 x 10⁻⁴.