Arrhenius Theory of Acids and Bases- Definitions, Types, Limitations, Practice Problems, FAQs

Can you guess the easiest way to differentiate an acid and a base using the tools of the chemistry laboratory?

Do you know that four different concepts were introduced to understand acid and base?

Arrhenius was the first to propose a theory on acids and bases, based on the release of ions and ions. Arrhenius's theory helps us to understand the difference between a lemon juice and bitter gourd scientifically and identify them using tools of the chemistry lab.

Table of contents

Arrhenius Acid
Types of Arrhenius acids
Arrhenius Base
Types of Arrhenius Base
Neutralisation
Advantages of Arrhenius concept
Limitation of Arrhenius Concept
Practice Problems
Frequently Asked Questions - FAQ

Arrhenius Acids

The substances that dissociate in water to give hydrogen ions () are Acids.

For example , , , etc dissociates to give ion and ion

dissociates in water to give hydrogen ions ()

The proton , cannot exist freely in aqueous solutions. It's associated with one or more water molecules as , or .

Association of with water molecules

Types of Arrhenius acids

Based on the number of ions dissociated by a molecule on dissolving in an ionizing solvent, acids

can be classified as follows:

Do you know how ????

Consider the oxyacids of phosphorus. Only those H-atom that is attached to the highly electronegative element will leave as an ion. Here, oxygen is highly electronegative, and therefore, the hydrogen attached to the oxygen only leaves as an ion. The P−H bond will not break as phosphorus is less electronegative.

Hence, is monobasic (only one O−H bond is present).

is dibasic (two O−H bonds are present).

is tribasic (three O−H bond present).

Polyprotic phosphoric acids

Arrhenius base

The substance that dissociates in water to give hydroxide ions (OH-) are Bases.

For example, BOH dissociates to give OH- ion and B+ ion

E.g. , , , etc

dissociates in water to give hydroxide ions (OH-)

Types of Arrhenius Base

Based on the number of ions dissociated by a molecule on dissolving in an ionizing solvent,

bases can be classified as follows:

Neutralization

Formation of salt and water by reaction of Acid with base is called Neutralisation.

Advantages of Arrhenius concept

It helps to understand the nature of a large number of acids and bases like etc.

Limitation of Arrhenius concept

It does not explain the acidic nature of compounds like etc.
It does not explain the basic character of certain compounds like etc.
It does not explain the behaviour of acids and bases in the absence of water.

Discussion on Acid-Bases, Ostwald's Dilution Law, Water, pH Scale | JEE

Practice Problems

Q 1. Identify the dibasic acid among the following.

a.
b.
c.
d.

Answer: (C)

being tribasic acid release three ions. & being monobasic acid release one ion. being dibasic acid release two ions. Hence the correct option is (C)

2. Which of the following is not an Arrhenius acid?

a.
b.
c.
d.

Answer : (D)

As per definition, Arrhenius acids are those substances which dissociate in water to give hydrogen ions (H+). Hence, is not considered Arrhenius Acid because it is not able to dissociate on its own .So, the correct option is (D).

Note: When is dissolved in water, lone pair of electrons of O in the ion will be taken by the empty p-orbital of boron and will form a bond, and the ion will remain in the solution to make it acidic.

3. Select monobasic Arrhenius acids from the following.

a.
b.
c.
d.

Answer : (B)

being tribasic acid release three ions. being monobasic acid release one ion. being dibasic acid release two ions. is not an Arrhenius acid. Hence correct option is (B)

4. Which of the following is a monoacidic Arrhenius Base?

a.
b.
c.
d.

Answer : (D)

being triacidic base release three ions. and being diacidic base release two ions. being monoacidic base release one ions. is not an arrhenius acid. Hence the correct option is (D)

Frequently Asked Questions – FAQs

Q 1. What are Polyprotic acids ?
Answer: Acids that can release more than one hydrogen ion are known as Polyprotic acids. For example, is diprotic acid as it can release two hydrogen ions upon dissociation.

Q 2. How not exhibit acidic nature as per Arrhenius concept?
Answer: As is not able to dissociate ion from its own. Hence, it does not exhibit acidic nature as per the Arrhenius concept.

Q 3. What is a diacidic base ?
Answer: Diacidic base means it is capable of reacting with two equivalent weights of an acid. That is why the diacidic term is included.

Q 4. What is a monobasic acid ?
Answer: Monobasic acid means it is capable of reacting with one equivalent weight of a base. That is why the monobasic term is included.

Related Topics