The pH of the solution is 3.63.
To solve this problem
Firstly, let calculate the moles of each substance
- Moles of HF: 0.25 M * 0.150 L = 0.0375 mol
- Moles of F⁻: 0.30 M * 0.225 L = 0.0675 mol
Secondly, let calculate the total volume of the solution
Total volume = 150.0 mL + 225.0 mL = 375.0 mL
Thirdly, let calculate the concentration of HF in the mixture
Concentration of HF = moles of HF / total volume
Concentration of HF = 0.0375 mol / 0.375 L = 0.1 M
Now, let calculate the concentration of F⁻ in the mixture
Concentration of F⁻ = moles of F⁻ / total volume
Concentration of F⁻ = 0.0675 mol / 0.375 L = 0.18 M
Let, Calculate the pKa of HF
pKa = -log(Ka)
pKa = -log(3.18 × 10⁻⁴) = 3.49
Finally, let calculate the pH of the solution using the Henderson-Hasselbalch equation
pH = pKa + log([F⁻] / [HF])
pH = 3.49 + log(0.18 / 0.1) = 3.63
So, the pH of the solution is 3.63.