Question

Which of the following describes what happens when a base is added to pure water?

Select the correct answer below:

The water donates a proton to the base, forming hydroxide ions and the conjugate acid.

The water dissociates into a hydronium ion and a hydroxide.

The base donates a proton to the free hydroxide ions, forming water molecules and the conjugate acid of the base.

The water dissociates into a proton and a hydroxide ion.

.

Answer 1

Correct answer is FIRST OPTION.

By definition, a base is a species that either donates an OH^{​​​​​-} ion(Arrhenius definition) or accepts an H⁺ ion(Bronsted Lowry definition).

A species formed after addition of an H⁺ ion to a base is called conjugate acid.

So, when a base is added to pure water, it accepts an H⁺ ion, and forms hydroxide ion and its conjugate acid. Example

NH_{​​​​​3} (base) + H₂O(acid) = NH_{​​​​​4}⁺ (conjugate acid) + OH^{​​​​​-}

(Please do give a thumbs up if you like this explanation. Your feedback fuels my efforts to improve myself)