Question

a solution is prepared by mixing 0.14 moles of acetic acid (ch3cooh) with 0.25 moles of sodium acetate (nach3coo) in 1.00 liters of solution. ka for acetic acid is 1.8 x 10-5. what will be the ph of the solution once equilibrium is established?

Answer 1

The equilibrium pH of the solution can be calculated using the Henderson-Hasselbalch equation. By inputting the provided molar concentrations for acetic acid and sodium acetate, along with the Ka value for acetic acid, the resultant pH can be determined.

Step-by-step explanation:

To calculate the equilibrium pH of the given solution, we can apply the Henderson-Hasselbalch equation for a buffer solution consisting of acetic acid (CH3COOH) and its conjugate base, sodium acetate (NaCH3COO). The formula for the Henderson-Hasselbalch equation is:

pH = pKa + log([A-]/[HA])

where:

• pKa is the negative logarithm of the acid dissociation constant (Ka).
• [A-] is the molar concentration of the conjugate base (acetate ion).
• [HA] is the molar concentration of the acid (acetic acid).

Using the values given:

• Number of moles of acetic acid = 0.14 moles
• Number of moles of sodium acetate = 0.25 moles
• Volume of solution = 1.00 liter
• pKa = -log(Ka) = -log(1.8 x 10^-5)

By substituting these values into the equation we get:

pH = -log(1.8 x 10^-5) + log(0.25/0.14)

Next, calculate the pH using the above formula. Remember that the molar concentration is simply the number of moles divided by the volume in liters, which in this case is 1 liter for both the acid and its conjugate base. Thus, the given values are also the concentrations in molarity.