Question

Determine the [OH-], pH and pOH of a solution with a [H+] of 1.5 x 10^-8 M at 25°C.

Options:
Option 1: [OH-]: 6.7 x 10^-7 M; pH: 7.82; pOH: 6.18
Option 2: [OH-]: 6.7 x 10^-8 M; pH: 6.82; pOH: 7.18
Option 3: [OH-]: 6.7 x 10^-9 M; pH: 5.82; pOH: 8.18
Option 4: [OH-]: 6.7 x 10^-6 M; pH: 8.82; pOH: 5.18

Answer 1

The correct option for the given hydronium ion concentration [H+] of 1.5 x 10^-8 M at 25°C is Option 1: [OH-]: 6.7 x 10^-7 M; pH: 7.82; pOH: 6.18.

Step-by-step explanation:

To find the concentration of hydroxide ions ([OH-]), the pH, and the pOH of a solution with a given hydronium ion concentration ([H+]) of 1.5 x 10^-8 M at 25°C, we can use the following relationships:

• The ion product constant of water (Kw) at 25°C is 1.0 x 10^-14 M^2.
• pH is calculated as -log [H+].
• pOH is calculated as -log [OH-].
• pH + pOH = 14.00 at 25°C.

First, we calculate the [OH-] using Kw and [H+]:

Kw = [H+] x [OH-]

[OH-] = Kw / [H+] = 1.0 x 10^-14 / 1.5 x 10^-8 = 6.7 x 10^-7 M

Next, we calculate the pH:

pH = -log [H+] = -log(1.5 x 10^-8) = 7.82

Finally, we calculate the pOH:

pOH = 14.00 - pH = 14.00 - 7.82 = 6.18

The correct option with the calculated values is: [OH-]: 6.7 x 10^-7 M; pH: 7.82; pOH: 6.18, which corresponds to Option 1.