Question

Find the [H+], [OH-], pH or pOH of the following:

a) pOH = 8.03 pH = ____________________

[OH-] = ___________________

[H3O+] = ____________________



b) [H3O+] = 4.36 x 10-2 pH = ____________________

pOH = ___________________

[OH-] = ___________________

Answer 1

a) Given pOH = 8.03, we can find the pH, [OH-], and [H3O+] using the following relationships:

pH + pOH = 14 (at 25°C)

1. pH = 14 - pOH
pH = 14 - 8.03
pH = 5.97

2. [OH-] = 10^(-pOH)
[OH-] = 10^(-8.03)
[OH-] ≈ 7.01 x 10^(-9) M

3. [H3O+] = 10^(-pH)
[H3O+] = 10^(-5.97)
[H3O+] ≈ 1.03 x 10^(-6) M

b) Given [H3O+] = 4.36 x 10^(-2) M, we can find the pH, pOH, and [OH-] using the following relationships:

1. pH = -log([H3O+])
pH = -log(4.36 x 10^(-2))
pH ≈ 1.36

2. pOH = 14 - pH
pOH = 14 - 1.36
pOH ≈ 12.64

3. [OH-] = 10^(-pOH)
[OH-] = 10^(-12.64)
[OH-] ≈ 3.98 x 10^(-13) M

So for the second case:
pH ≈ 1.36
pOH ≈ 12.64
[OH-] ≈ 3.98 x 10^(-13) M

Hope this helps you.
willkiddhill