pOH of H3O+] = 0.00020

To find the pOH of a solution with a given concentration of hydronium ions ([H3O+]), we can use the following formula:

pOH = -log[H3O+]

Given that the concentration of hydronium ions is 0.00020 M, we can plug this value into the formula:

pOH = -log(0.00020)

pOH ≈ -log(2.0 x 10^-4)

pOH ≈ -(-3.70)

pOH ≈ 3.70

Therefore, the pOH of a solution with a hydronium ion concentration of 0.00020 M is approximately 3.70.