<u>Answer:</u> The pH of acid solution is 4.58
<u>Explanation:</u>
To calculate the number of moles for given molarity, we use the equation:
.....(1)
Molarity of KOH solution = 1.1000 M
Volume of solution = 41.04 mL
Putting values in equation 1, we get:

- <u>For propanoic acid:</u>
Molarity of propanoic acid solution = 0.6100 M
Volume of solution = 224.9 mL
Putting values in equation 1, we get:

The chemical reaction for propanoic acid and KOH follows the equation:

<u>Initial:</u> 0.1372 0.04514
<u>Final:</u> 0.09206 - 0.04514
Total volume of solution = [224.9 + 41.04] mL = 265.94 mL = 0.26594 L (Conversion factor: 1 L = 1000 mL)
To calculate the pH of acidic buffer, we use the equation given by Henderson Hasselbalch:
![pH=pK_a+\log(\frac{[\text{salt}]}{[acid]})](https://tex.z-dn.net/?f=pH%3DpK_a%2B%5Clog%28%5Cfrac%7B%5B%5Ctext%7Bsalt%7D%5D%7D%7B%5Bacid%5D%7D%29)
![pH=pK_a+\log(\frac{[C_2H_5COOK]}{[C_2H_5COOH]})](https://tex.z-dn.net/?f=pH%3DpK_a%2B%5Clog%28%5Cfrac%7B%5BC_2H_5COOK%5D%7D%7B%5BC_2H_5COOH%5D%7D%29)
We are given:
= negative logarithm of acid dissociation constant of propanoic acid = 4.89
![[C_2H_5COOK]=\frac{0.04514}{0.26594}](https://tex.z-dn.net/?f=%5BC_2H_5COOK%5D%3D%5Cfrac%7B0.04514%7D%7B0.26594%7D)
![[C_2H_5COOH]=\frac{0.09206}{0.26594}](https://tex.z-dn.net/?f=%5BC_2H_5COOH%5D%3D%5Cfrac%7B0.09206%7D%7B0.26594%7D)
pH = ?
Putting values in above equation, we get:

Hence, the pH of acid solution is 4.58