CALCULATE PH OF THE SOLUTION THAT RESULTS FROM EACH SOLUTION
A) 150.0mL OF 0.25M HF WITH 225.0 mL OF 0.30M NaF
Help please, these buffer questions are confusing.
Just calculate the mols (or the molarity of each) and plug into the Henderson-Hasselbalch equation.
To calculate the pH of a solution resulting from a buffer solution, you need to consider the equilibrium between the weak acid (HF) and its conjugate base (F-) in the presence of their respective concentrations.
A buffer solution is formed when a weak acid and its conjugate base are present in roughly equal concentrations. In this case, we have HF as the weak acid and NaF as its conjugate base.
To calculate the pH, we can use the Henderson-Hasselbalch equation, which is as follows:
pH = pKa + log ([A-] / [HA])
Where:
pH = the pH of the solution
pKa = the acid dissociation constant of the weak acid
[A-] = concentration of the conjugate base
[HA] = concentration of the weak acid
Now, let's step through the calculation:
1. Calculate the moles of solute for each species.
Moles of HF = (0.25 mol/L) * (0.150 L) = 0.0375 mol
Moles of NaF = (0.30 mol/L) * (0.225 L) = 0.0675 mol
2. Calculate the total volume of the solution.
Total volume = volume of HF + volume of NaF = 150.0 mL + 225.0 mL = 375.0 mL = 0.375 L
3. Calculate the molar concentration of each species.
Concentration of HF = (0.0375 mol) / (0.375 L) = 0.10 M
Concentration of NaF = (0.0675 mol) / (0.375 L) = 0.18 M
4. Calculate the pKa of HF.
The pKa value for HF is around 3.17.
5. Apply the Henderson-Hasselbalch equation to calculate the pH.
pH = 3.17 + log (0.18 / 0.10)
= 3.17 + log (1.8)
= 3.17 + 0.255
= 3.425
The pH of the resulting buffer solution containing 150.0 mL of 0.25 M HF and 225.0 mL of 0.30 M NaF is approximately 3.425.