If the hydroxide ion concentration of a solution is 1.0 x 10^5, we can use the following formula to calculate the pOH:
pOH = -log[OH-]
where [OH-] is the concentration of hydroxide ions in moles per liter.
Substituting the given value, we get:
pOH = -log(1.0 x 10^5)
pOH = -5
To find the pH of the solution, we can use the fact that pH + pOH = 14 (for a neutral solution at 25°C). Rearranging this equation, we get:
pH = 14 - pOH
Substituting the pOH value we just found, we get:
pH = 14 - (-5)
pH = 19
Since the pH of the solution is greater than 14, which is not possible for an aqueous solution at 25°C, it means that the given hydroxide ion concentration of 1.0 x 10^5 is not physically possible. Therefore, we cannot determine whether the solution is an acid or a base based on this information.