Question

Calculate the pH of 0.167 M pyridinium chloride, C₅H₅NHCl. The ionization constant of pyridine, C₅H₅N, is Kb = 1.7 × 10⁻⁹.

Answer 1

To calculate the pH of a 0.167 M solution of pyridinium chloride, we can use the Henderson-Hasselbalch equation. The pKa value for the pyridinium ion can be calculated using the equilibrium constant Kb. By substituting the pKa value into the Henderson-Hasselbalch equation, we can determine the pH of the solution.

Step-by-step explanation:

The pH of a 0.167 M solution of pyridinium chloride can be calculated using the Henderson-Hasselbalch equation. First, we need to determine the pKa value for the pyridinium ion. To do this, we can use the equation pKa + pKb = pKw, where pKa is the negative logarithm of the acid dissociation constant (Ka), pKb is the negative logarithm of the base dissociation constant (Kb), and pKw is the negative logarithm of the water dissociation constant (Kw). Given that the Kb value for pyridine is 1.7 × 10⁻⁹, we can calculate the pKa value as follows:

pKa = pKw - pKb = 14.00 - 8.77 = 5.23

Now we can substitute the pKa value into the Henderson-Hasselbalch equation:

pH = pKa + log([base]/[acid])