Buffer Solutions

Answer (c) increases by one

Step 1: Understanding the System.
We are mixing pyridine (C H N, a weak base) with its conjugate acid, pyridinium chloride (C H NH Cl ). This combination forms a basic buffer solution.
Step 2: Calculate the concentrations of the base and its conjugate acid.
Volume of solution = 500 cm = 0.5 L.
Concentration of pyridine (Base): [Base] = [C H N] = 0.2 M (given).
Concentration of pyridinium chloride (Salt/Conjugate Acid): Moles of salt = 0.15 mol. Step 3: Key Formula for Buffer pH (Henderson-Hasselbalch Equation).
For a basic buffer, we can calculate the pOH using the Henderson-Hasselbalch equation: And then find pH using pH + pOH = 14.
Step 4: Calculate pK .
K = 1.5 10 . Given log(1.5) 0.18. Step 5: Calculate pOH.
Step 6: Calculate pH.
Step 7: Final Answer.
The pH of the resulting buffer solution is 5.