Question

which of these correctly defines the poh of a solution?
the log of the hydronium ion concentration
the negative log of the hydronium ion concentration
the log of the hydroxide ion concentration
the negative log of the hydroxide ion concentration

Explanation:

1. Recall the definition of pOH: The pOH of a solution is defined as the negative logarithm (base 10) of the hydroxide ion ($\ce{OH^-}$) concentration.
2. Analyze the other options:

• The log of the hydronium ion concentration is not related to pOH (hydronium is $\ce{H3O^+}$, related to pH).
• The negative log of the hydronium ion concentration is the definition of pH, not pOH.
• The log of the hydroxide ion concentration is not the definition of pOH (it's the negative log).

So the correct definition is the negative log of the hydroxide ion concentration.

Answer:

D. the negative log of the hydroxide ion concentration