Respuesta :
Answer:
the pH of the buffer solution is approximately 4.74.
Explanation:
To find the pH of a butter solution, you can use the Henderson-Hasselbalch equation:
pH = pKa + log A HA
Where:
* pH is the acidity of the solution.
pka is the negative logarithm (base 10) of the acid dissociation constant (Ka) of the weak acid.
* A^-is the concentration of the conjugate base (CH₂COO).
• HA is the concentration of the weak acid (CH2COOH).
Given that the Ka of CH₂COOH is 1.8 × 105, the pKa is-log(1.8 × 10-5).
pKa = log(1.8 x 10-5)
Now, let's substitute the values into the Henderson-Hasselbalch equation: pH = -log(1.8 × 10-5) + log (CHCOOH
You mentioned the concentrations are both 0.5M, so let's substitute that in:
pH = -log(1.8 × 10-5) + log 0.5 0.5
Now, calculate the values and add them up:
pH = -log(1.8 × 10-5) + log(1)
pH = -log(1.8 × 10-5)
Now, calculate the pH:
pH ≈ 4.74
Therefore, the pH of the buffer solution is approximately 4.74.
Final answer:
To calculate the pH of the buffer solution, the Henderson-Hasselbalch equation is used, and with equal concentrations of acetic acid and acetate ion, the pH is equal to the pKa, which is 4.74.
Explanation:
The question asks about the pH of a buffer solution composed of equimolar concentrations of acetic acid (CH3COOH) and sodium acetate (CH3COONa), with a given acid dissociation constant (ka) for acetic acid.
To calculate the pH, we will use the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), First, let's find the pKa, which is the negative logarithm of the Ka: pKa = -log(Ka) = -log(1.8*10^-5) = 4.74
Since the concentrations of acetic acid (CH3COOH) and the acetate ion (CH3COO^-) from sodium acetate (CH3COONa) are equal, their ratio is 1, and log(1) is 0. Therefore, the pH of the buffer is simply equal to the pKa: pH = pKa = 4.74
