Question

to study the effects of a weakly acidic medium on the rate of corrosion of a metal alloy, a student prepared a buffer solution containing both 0.110 M Na C2H3O2 and 0.090 M HC2H3O2. What is the pH of this solution

Answer 1

Answer: The pH of the buffer solution is approximately 1.05.

Step-by-step explanation:

The dissociation reaction of acetic acid is as follows:

HC2H3O2 ⇌ H+ + C2H3O2-

The equilibrium constant expression for this reaction is:

K_a = [H+][C2H3O2-] / [HC2H3O2]

In a buffer solution,

concentration of HC2H3O2 = concentration of C2H3O2- =0.090M

Now, we can substitute the given values into the equilibrium constant expression:

K_a = [H+][0.090] / [0.090]

K_a = [H+]

Since the concentration of acetic acid and acetate ion are equal in the buffer solution, the equilibrium constant is approximately equal to the concentration of the hydrogen ions ([H+]). Thus, the concentration of hydrogen ions in the buffer solution is 0.090 M.

To find the pH, we can use the logarithmic scale of acidity:

pH = -log[H+]

Substituting the value of [H+] into the equation:

pH = -log(0.090)

pH ≈ 1.05