Question

What is an Arrhenius base?
A) Species that increases the concentration of \[{H^ + }\] ions.
B) Species that increase the concentration of \[O{H^ - }\]ions.
C) Species that increases the concentration of both \[{H^ + }\]and \[O{H^ - }\]ions.
D) None of these

Answer 1

Hint: We need to remember that It is easy to identify a base and an acid. A base usually contains a hydroxide ion. For example:\[NaOH\], \[KOH\]. Whereas, an acid contains \[{H^ + }\] ions in it. For example: \[HCl\], \[{H_2}S{O_4}\].

Complete answer:
Option A) this is an incorrect option as the species that increases the concentration of \[{H^ + }\]ions is termed as Arrhenius acid.
We can understand this by looking at this example:
On making an aqueous solution of \[HCl\], it dissociates itself into \[{H^ + }\] and \[C{l^ - }\] ions.
\[HCl \to {H^ + } + C{l^ - }\]
As the concentration of \[{H^ + }\] increases in the solution, thus \[HCl\] is an Arrhenius acid.
Option B) this is a correct option as the species that increases the concentration of \[O{H^ - }\] ions is termed as Arrhenius base.
We can have a look at an example to understand this well.
In water \[KOH\] fully dissociates in water to give \[{K^ + }\] and \[O{H^ - }\] ions.
\[KOH \to {K^ + } + O{H^ - }\]
As the concentration of \[O{H^ - }\] (hydroxide ion) increases in the solution, thus \[KOH\] is an Arrhenius base.
So this is a correct option that defines Arrhenius base.
Option C) this is an incorrect option, as both Arrhenius base and Arrhenius acid reacts together to form water and a salt.
For example:
\[HF + LiOH \to {H_2}O + LiF\]
Option D) this is an incorrect option.

So we get Option B as a correct answer.

Note:
Sometimes, when an Arrhenius base reacts with an Arrhenius acid the products so formed are water and a salt, this type of reaction may be called a Neutralization reaction. Also, Arrhenius theory is limited to acid-base chemistry only.