Question

A solution is prepared at that is initially in diethylamine , a weak base with , and in diethylammonium chloride . Calculate the pH of the solution. Round your answer to decimal places.

Answer 1

Answer:

10.96

Explanation:

A solution is prepared at 25 °C that is initially 0.14 M in diethylamine, a weak base with Kb = 1.3 × 10⁻³, and 0.20 M in diethylammonium chloride. Calculate the pH of the solution. Round your answer to 2 decimal places.

Step 1: Calculate the pOH of the solution

Diethylamine is a weak base and diethylammonium (from diethylammonium chloride) its conjugate acid. Thus, they form a buffer system. We can calculate the pOH of this buffer system using the Henderson-Hasselbach's equation.

pOH = pKb + log [acid]/[base]

pOH = -log 1.3 × 10⁻³ + log 0.20 M/0.14 M

pOH = 3.04

Step 2: Calculate the pH of the solution

We will use the following expression.

pH + pOH = 14

pH = 14 - pOH = 14 -3.04 = 10.96