Final answer:
The pOH of a solution with an OH- ion concentration of 6.0E-4 is 3.22, calculated by taking the negative log of the hydroxide ion concentration.
Step-by-step explanation:
To calculate the pOH of a solution with an OH- ion concentration of 6.0E-4, you take the negative logarithm of the hydroxide ion concentration. Doing so, you get:
pOH = -log [OH-]
pOH = -log(6.0 × 10-4)
pOH = 3.22
That's the pOH of the solution. To find the pH, you would subtract the pOH from 14 (since pH + pOH = 14 for any aqueous solution at 25°C), but since the question only asks for pOH, that additional calculation isn't necessary here.