Question

The pH of a solution of CH₃NH₂ is 8.45 at 25 °C. What is the hydroxide ion concentration in this solution?

Answer 1

To determine the hydroxide ion concentration from a pH of 8.45, one must first calculate the pOH by subtracting the pH from 14, and then use the pOH to calculate the hydroxide ion concentration using the formula [OH-] = 10^-pOH.

Step-by-step explanation:

To find the hydroxide ion concentration in a solution with a given pH, we first calculate the pOH of the solution, and then use the pOH to find the hydroxide ion concentration. Since the pH of the CH₃NH₂ solution is provided as 8.45, we can proceed with the following calculations:

1. Calculate the pOH of the solution:
2. pOH = 14.00 - pH = 14.00 - 8.45 = 5.55
3. Calculate the hydroxide ion concentration from the pOH:
4. [OH⁻] = 10⁻pOH = 10⁻⁻.55 = 2.82 x 10⁻6 M

The hydroxide ion concentration in the solution at 25 ℃ is 2.82 x 10⁻6 M.