Question: What is the substance that forms Hydronium ion in water (Arrhenius)? A) Base B) \[KOH\] C) Aci...

Question

What is the substance that forms Hydronium ion in water (Arrhenius)?
A) Base
B) $KOH$
C) Acid
D) None of these

Answer 1

Solution

It is easy to identify a base and an acid. A base usually contains a hydroxide ion $(OH^-)$ and an acid contains ${H^ + }$ ion. We have to know that an acid is any hydrogen-containing substance that is capable of donating a proton (hydrogen ion) to another substance. A base is a molecule or ion able to accept a hydrogen ion from an acid.

Complete answer:
Before solving this question we must know what Arrhenius base and acid are?
Arrhenius acid:
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.
Arrhenius base:
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 A) this is an incorrect option, as a base does not release ${H^ + }$ instead it increases the concentration of $O{H^ - }$ ions thus this option is not correct.
Option B) this is an incorrect option, as just now we have discussed that a base does not release ${H^ + }$ and $KOH$ is a base.
Option C) this is a correct option as acid is a substance that forms hydronium ions in water.
According to Arrhenius concept, an acid when dissolved in water releases ${H^ + }$ since when an Arrhenius acid releases ${H^ + }$ , ${H_2}O$ molecule accept it forming Hydronium ion( ${H_3}{O^ + }$ )
${H_2}O + {H^ + } \to {H_3}{O^ + }$
Option D) this is an incorrect option .

Option C as the correct answer.

Note:
We have to remember that 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.