Final answer:
The pOH of a solution with a hydronium ion concentration of 8.4 x 10^-3 M is calculated to be 11.924.
Step-by-step explanation:
If the hydronium ion concentration ([H3O+]) of a solution is 8.4 x 10-3 M, we can calculate the pOH of the solution by first determining the pH and then using the relationship pH + pOH = 14.00.
To find the pH, we use the formula pH = -log [H3O+].
First, calculate the pH:
pH = -log (8.4 x 10-3)
= 2.076.
Next, since pH + pOH = 14.00, we can find pOH:
pOH = 14.00 - pH
= 14.00 - 2.076
= 11.924.
Therefore, the pOH of the solution is 11.924.