Question

What is the pH of 0.150 M C₃H₇NH₃I? The Kb of C₃H₇NH₂ is 3.5 × 10⁻⁴.

a) 3.85
b) 4.25
c) 4.65
d) 5.10

Answer 1

To determine the pH of a solution of C₃H₇NH₃I, we need to consider its basicity and the Kb value of C₃H₇NH₂. The pH of the solution is approximately 3.85 (option a).

Step-by-step explanation:

To determine the pH of a solution of C₃H₇NH₃I, we need to consider its basicity and the Kb value of C₃H₇NH₂.

The Kb value of C₃H₇NH₂ is 3.5 × 10⁻⁴. Since C₃H₇NH₃I is a salt of C₃H₇NH₃⁺ and I⁻, it will react with water to form C₃H₇NH₃ and HI.

To find the pH, we need to calculate the concentration of OH⁻, which can be done by using the Kb value:

Kb = [C₃H₇NH₃][OH⁻] / [C₃H₇NH₂]

[OH⁻] = Kb * [C₃H₇NH₂] / [C₃H₇NH₃]

Since [C₃H₇NH₃I] = [C₃H₇NH₃], we can substitute [C₃H₇NH₃I] for [C₃H₇NH₃] and rearrange the equation to find [OH⁻].

The pH is then calculated as pH = -log[H₃O⁺], where [H₃O⁺] = Kw / [OH⁻].

Using the given information, the pH of the solution is approximately 3.85 (option a).