Answer:
pOH = 9.
Step-by-step explanation:
The inverse relationship between the pH and pOH of any given solution can be written as:
pH = 14 - pOH
Or conversely:
pOH = 14 - pH
With the above information in mind we can use the given pH to calculate the pOH:
pOH = 14 - pH
pOH = 14 - 5
pOH = 9
Thus, black coffee has a pOH of 9.