Ionization of Acids and Bases-Arrhenius Acid Base Theory

February 11, 2025December 14, 2024 by Neeraj Anand, Param Anand

Ionization of a compound in Chemistry is the process by which neutral molecules are divided into charged ions in a solution.

According to the Arrhenius Theory, acids are substances that dissociate in an aqueous medium to produce hydrogen ions, H⁺ions, and bases are substances that dissociate in an aqueous medium producing OH^– ions. The strength of acids and bases can be defined based on the degree of ionization of acids and bases.

Here in this article, we will learn about, Ionization Definition, Arrhenius Concept of Acid and Base, and Explanation of Arrhenius Acid and Base Ionization concept, Examples, and others in detail.

What is Ionization?

Ionization of a compound is defined as the process in which a compounds dissociates into its constituent ions. When a compound whether acidic or basic is dissolved into an aqueous solution, they dissociate into positive and negative ion respectively. In case of acids, the H+ ions are release and in case of base OH- ions are released. Sometimes, the ionization is not easy such as in salts. The compounds that is to be dissolved in the given solvent is called the electrolyte and its dissociation is measured in form of degree of dissociation.

Degree of Ionization

Degree of Ionization of any compound is defined as the ratio of the number of molecule undergoing dissociation to total number of molecules of the compound. It is defined using the symbol “α”(Degree of Ionization)

Arrhenius Concept of Acid and Base Ionization

Arrhenius explain the concept of acid and base as the compounds that in aqueous medium generates ions. “An acid is a compound that produces an Hydrogen Ions(H⁺) in the aqueous solution” whereas “Base is a compouns that produces Hydoxyl Ions(OH^–) in the aqueous medium.”

Ionization of Acid(HCl)

HCl(aq.) → H⁺ + Cl^–

Ionization of Base(KOH)

KOH(aq.) → K⁺ + OH^–

Explanation of Arrhenius Acid and Base Ionization

Accoring to Arrhenius, the dissociation equillibrium of acid and base are dynamic in nature. Suppose we take an acid HA and HA has higher tendency to donate eclectrons than H3O⁺ then in that case HA acts as strong acid.

HA + H₂O ⇌ H₃O⁺ + A^–

Now, stronger acid denotes protons the equlibrium moves in the direction of formation weaker base. This implies that a strong acid generally have a weaker base.

Ionization of Acid and Base

Degree of ionisation of the acids and bases contributes to their strength. The degree of ionisation might vary depending on the acidic and basic substances. Ionization constant of acid and base is the constant that tells us the strength of acid and the base. Higher the dissociation constant of acid and base higher is the strength of acid and base.

Ionization of Acids

Degree of ionisation refers to the acidity or baseness of an acid or base. A strong acid ionizes completely in the water, whereas a weak acid just ionizes partially in the aqueous solution. Now an Arrhenius Acid ionizes as,

HA (aq) + H₂O ⇌ H₃O⁺ (aq) + A^–

Now, the equllibrium constant is,

K_a = [H₃O⁺] [A^–] / [HA]

where K_a is the ionization constant of acid and hiher the value of K_a higher is the strength of the acid.

Ionization of Bases

In an aqueous solution, some bases, such as Lithium Hydroxide or Sodium Hydroxide, totally dissociate into their ions and are referred to as strong bases. Now an Arrhenius Base ionizes as,

A + H₂O ⇌ OH^– + HA⁺

Now, the equllibrium constant is,

K_b = [OH^–] [HA⁺] / [A]

where K_b is the base ionization constant and higher value of K_b represent the higher strength of the base.

Acid and Base Ionization Example

Ionization of various acid and bases are added below,

Ionization of Acid

The ionization of some popular acids are discussed below:

HCl (Hydrochloric Acid) is a strong acid and it ionizes as,

HCl + H₂O ⇌ Cl^– + H₃O⁺

CH₃COOH (Acetic Acid) is a weak acid and it ionizes as,

CH₃COOH + H₂O ⇌ CH₃COO^‾ + H₃O⁺

Ionization of Base

The ionization of some popular bases are discussed below:

NaOH (Sodim Hydroxide) is a strong base and it ionizes as,

NaOH + H₂O ⇌ Na⁺ + OH^–

NH4OH (Ammonium Hydroxide)is a weak base and it ionizes as,

NH₃ + H₂O ⇌ NH₄⁺ (aq) + OH^‾(aq)

Read More,

Acid and Base Ionization – FAQs

1. What are Acids and Bases?

Acids are the compounds that release H⁺ ion in aqueous solution and have a highly sour flavour. Orange juice and lemon juice are two examples of acids. Bases he compounds that release OH^– ion in aqueous solution have a more harsh flavour. As an example of a base, consider soap (made of magnesium hydroxide or potassium salts).

2. What does Ionization of Base mean?

In an aqueous media known as a strong base, some bases, such as lithium hydroxide and sodium hydroxide, are totally dissociated into ions. As a result, the ionisation of these bases results in the formation of hydrogen chloride ions, such as (OH^–).

3. What does Ionization of Acid mean?

The degree of ionisation is determined by the acid or base strength. Strong acids are totally ionised in water, whereas weak acids are just partially ionised. Because the degree of acid ionisation varies, so does the degree of weakening.

4. How to know if Something Ionizes Completely?

Degree of disassociation of any compound tells us the percent of the ionization of that compound. So if the degree of ionization of any compound is 1 it tells us that the compound ionizes completely.

5. What is Percent Ionization Formula?

Percent ionization formula of weak acid or weak base is,

Percent Ionization = (Concentration of Ionized Weak Acid Or Base)/(Initial Concentration of Acid or Base) × 100

6. Does the Ionization of an Acid or Base Increase with Dilution?

Ionization of weak electrolytes, i.e. Acids or Bases increases with the increases in the dilution of the solution.

7. What happens when a Base reacts with an Acid?

When a base reacts with an acid neutralization rections occurs. In this reaction acid neutralizes base and salt and water is formed. For example a neutralization reaction is,

HCl + NaOH ⇌ NaCl + H₂O

Neeraj Anand, Param Anand

Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations. In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS". He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.

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CBSE Class 11 Chemistry Syllabus

CBSE Class 11 Chemistry Syllabus is a vast which needs a clear understanding of the concepts and topics. Knowing CBSE Class 11 Chemistry syllabus helps students to understand the course structure of Chemistry.

Unit-wise CBSE Class 11 Syllabus for Chemistry

Below is a list of detailed information on each unit for Class 11 Students.

UNIT I – Some Basic Concepts of Chemistry

General Introduction: Importance and scope of Chemistry.

Nature of matter, laws of chemical combination, Dalton’s atomic theory: concept of elements,
atoms and molecules.

Atomic and molecular masses, mole concept and molar mass, percentage composition, empirical and molecular formula, chemical reactions, stoichiometry and calculations based on stoichiometry.

UNIT II – Structure of Atom

Discovery of Electron, Proton and Neutron, atomic number, isotopes and isobars. Thomson’s model and its limitations. Rutherford’s model and its limitations, Bohr’s model and its limitations, concept of shells and subshells, dual nature of matter and light, de Broglie’s relationship, Heisenberg uncertainty principle, concept of orbitals, quantum numbers, shapes of s, p and d orbitals, rules for filling electrons in orbitals – Aufbau principle, Pauli’s exclusion principle and Hund’s rule, electronic configuration of atoms, stability of half-filled and completely filled orbitals.

UNIT III – Classification of Elements and Periodicity in Properties

Significance of classification, brief history of the development of periodic table, modern periodic law and the present form of periodic table, periodic trends in properties of elements -atomic radii, ionic radii, inert gas radii, Ionization enthalpy, electron gain enthalpy, electronegativity, valency. Nomenclature of elements with atomic number greater than 100.

UNIT IV – Chemical Bonding and Molecular Structure

Valence electrons, ionic bond, covalent bond, bond parameters, Lewis structure, polar character of covalent bond, covalent character of ionic bond, valence bond theory, resonance, geometry of covalent molecules, VSEPR theory, concept of hybridization, involving s, p and d orbitals and shapes of some simple molecules, molecular orbital theory of homonuclear diatomic molecules(qualitative idea only), Hydrogen bond.

UNIT V – Chemical Thermodynamics

Concepts of System and types of systems, surroundings, work, heat, energy, extensive and intensive properties, state functions. First law of thermodynamics – internal energy and enthalpy, measurement of U and H, Hess’s law of constant heat summation, enthalpy of bond dissociation, combustion, formation, atomization, sublimation, phase transition, ionization, solution and dilution. Second law of Thermodynamics (brief introduction)
Introduction of entropy as a state function, Gibb’s energy change for spontaneous and nonspontaneous processes.
Third law of thermodynamics (brief introduction).

UNIT VI – Equilibrium

Equilibrium in physical and chemical processes, dynamic nature of equilibrium, law of mass action, equilibrium constant, factors affecting equilibrium – Le Chatelier’s principle, ionic equilibrium- ionization of acids and bases, strong and weak electrolytes, degree of ionization,
ionization of poly basic acids, acid strength, concept of pH, hydrolysis of salts (elementary idea), buffer solution, Henderson Equation, solubility product, common ion effect (with illustrative examples).

UNIT VII – Redox Reactions

Concept of oxidation and reduction, redox reactions, oxidation number, balancing redox reactions, in terms of loss and gain of electrons and change in oxidation number, applications of redox reactions.

UNIT VIII – Organic Chemistry: Some basic Principles and Techniques

General introduction, classification and IUPAC nomenclature of organic compounds. Electronic displacements in a covalent bond: inductive effect, electromeric effect, resonance and hyper conjugation. Homolytic and heterolytic fission of a covalent bond: free radicals, carbocations, carbanions, electrophiles and nucleophiles, types of organic reactions.

UNIT IX – Hydrocarbons

Classification of Hydrocarbons
Aliphatic Hydrocarbons:
Alkanes – Nomenclature, isomerism, conformation (ethane only), physical properties, chemical reactions.
Alkenes – Nomenclature, structure of double bond (ethene), geometrical isomerism, physical properties, methods of preparation, chemical reactions: addition of hydrogen, halogen, water, hydrogen halides (Markovnikov’s addition and peroxide effect), ozonolysis, oxidation, mechanism of electrophilic addition.
Alkynes – Nomenclature, structure of triple bond (ethyne), physical properties, methods of preparation, chemical reactions: acidic character of alkynes, addition reaction of – hydrogen, halogens, hydrogen halides and water.

Aromatic Hydrocarbons:

Introduction, IUPAC nomenclature, benzene: resonance, aromaticity, chemical properties: mechanism of electrophilic substitution. Nitration, sulphonation, halogenation, Friedel Craft’s alkylation and acylation, directive influence of functional group in monosubstituted benzene. Carcinogenicity and toxicity.

To know the CBSE Syllabus for all the classes from 1 to 12, visit the Syllabus page of CBSE. Meanwhile, to get the Practical Syllabus of Class 11 Chemistry, read on to find out more about the syllabus and related information in this page.

CBSE Class 11 Chemistry Practical Syllabus with Marking Scheme

In Chemistry subject, practical also plays a vital role in improving their academic scores in the subject. The overall weightage of Chemistry practical mentioned in the CBSE Class 11 Chemistry syllabus is 30 marks. So, students must try their best to score well in practicals along with theory. It will help in increasing their overall academic score.

CBSE Class 11 Chemistry Practical Syllabus

The experiments will be conducted under the supervision of subject teacher. CBSE Chemistry Practicals is for 30 marks. This contribute to the overall practical marks for the subject.

The table below consists of evaluation scheme of practical exams.

Evaluation Scheme	Marks
Volumetric Analysis	08
Salt Analysis	08
Content Based Experiment	06
Project Work	04
Class record and viva	04
Total	30

CBSE Syllabus for Class 11 Chemistry Practical

Micro-chemical methods are available for several of the practical experiments. Wherever possible such techniques should be used.

A. Basic Laboratory Techniques
1. Cutting glass tube and glass rod
2. Bending a glass tube
3. Drawing out a glass jet
4. Boring a cork

B. Characterization and Purification of Chemical Substances
1. Determination of melting point of an organic compound.
2. Determination of boiling point of an organic compound.
3. Crystallization of impure sample of any one of the following: Alum, Copper Sulphate, Benzoic Acid.

C. Experiments based on pH

1. Any one of the following experiments:

Determination of pH of some solutions obtained from fruit juices, solution of known and varied concentrations of acids, bases and salts using pH paper or universal indicator.
Comparing the pH of solutions of strong and weak acids of same concentration.
Study the pH change in the titration of a strong base using universal indicator.

2. Study the pH change by common-ion in case of weak acids and weak bases.

D. Chemical Equilibrium
One of the following experiments:

1. Study the shift in equilibrium between ferric ions and thiocyanate ions by increasing/decreasing the concentration of either of the ions.
2. Study the shift in equilibrium between [Co(H₂O)₆] ²⁺ and chloride ions by changing the concentration of either of the ions.

E. Quantitative Estimation
i. Using a mechanical balance/electronic balance.
ii. Preparation of standard solution of Oxalic acid.
iii. Determination of strength of a given solution of Sodium hydroxide by titrating it against standard solution of Oxalic acid.
iv. Preparation of standard solution of Sodium carbonate.
v. Determination of strength of a given solution of hydrochloric acid by titrating it against standard Sodium Carbonatesolution.

F. Qualitative Analysis
1) Determination of one anion and one cation in a given salt
Cations‐ Pb²⁺, Cu²⁺, As³⁺, Al³⁺, Fe³⁺, Mn²⁺, Ni²⁺, Zn²⁺, Co²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mg²⁺, NH₄ ⁺
Anions – (CO₃)^2‐ , S^2‐, NO₂^‐ , SO₃^2‐, SO^2‐ , NO ^‐ , Cl^‐ , Br^‐, I‐, PO₄^3‐ , C₂O²‐ ,CH₃COO^‐
(Note: Insoluble salts excluded)

2) Detection of ‐ Nitrogen, Sulphur, Chlorine in organic compounds.

G) PROJECTS
Scientific investigations involving laboratory testing and collecting information from other sources.

A few suggested projects are as follows:

Checking the bacterial contamination in drinking water by testing sulphide ion
Study of the methods of purification of water.
Testing the hardness, presence of Iron, Fluoride, Chloride, etc., depending upon the regional
variation in drinking water and study of causes of presence of these ions above permissible
limit (if any).
Investigation of the foaming capacity of different washing soaps and the effect of addition of
Sodium carbonate on it.
Study the acidity of different samples of tea leaves.
Determination of the rate of evaporation of different liquids Study the effect of acids and
bases on the tensile strength of fibres.
Study of acidity of fruit and vegetable juices.

Note: Any other investigatory project, which involves about 10 periods of work, can be chosen with the approval of the teacher.

Practical Examination for Visually Impaired Students of Class 11

Below is a list of practicals for the visually impaired students.

A. List of apparatus for identification for assessment in practicals (All experiments)
Beaker, tripod stand, wire gauze, glass rod, funnel, filter paper, Bunsen burner, test tube, test tube stand,
dropper, test tube holder, ignition tube, china dish, tongs, standard flask, pipette, burette, conical flask, clamp
stand, dropper, wash bottle
• Odour detection in qualitative analysis
• Procedure/Setup of the apparatus

B. List of Experiments A. Characterization and Purification of Chemical Substances
1. Crystallization of an impure sample of any one of the following: copper sulphate, benzoic acid
B. Experiments based on pH
1. Determination of pH of some solutions obtained from fruit juices, solutions of known and varied
concentrations of acids, bases and salts using pH paper
2. Comparing the pH of solutions of strong and weak acids of same concentration.

C. Chemical Equilibrium
1. Study the shift in equilibrium between ferric ions and thiocyanate ions by increasing/decreasing
the concentration of eitherions.
2. Study the shift in equilibrium between [Co(H2O)6]2+ and chloride ions by changing the
concentration of either of the ions.

D. Quantitative estimation
1. Preparation of standard solution of oxalic acid.
2. Determination of molarity of a given solution of sodium hydroxide by titrating it against standard
solution of oxalic acid.

E. Qualitative Analysis
1. Determination of one anion and one cation in a given salt
2. Cations – NH+4
Anions – (CO3)2-, S2-, (SO3)2-, Cl-, CH3COO-
(Note: insoluble salts excluded)
3. Detection of Nitrogen in the given organic compound.
4. Detection of Halogen in the given organic compound.

Note: The above practicals may be carried out in an experiential manner rather than recording observations.

We hope students must have found this information on CBSE Syllabus useful for their studying Chemistry. Learn Maths & Science in interactive and fun loving ways with ANAND CLASSES (A School Of Competitions) App/Tablet.

Frequently Asked Questions on CBSE Class 11 Chemistry Syllabus

How many units are in the CBSE Class 11 Chemistry Syllabus?

There are 9 units in the CBSE Class 11 Chemistry Syllabus. Students can access various study materials for the chapters mentioned in this article for free at ANAND CLASSES (A School Of Competitions).

What is the total marks for practicals examination as per the CBSE Class 11 Chemistry Syllabus?

The total marks for the practicals as per the CBSE Class 11 Chemistry Syllabus is 30. It includes volumetric analysis, content-based experiment, salt analysis, class record, project work and viva.

Which chapter carries more weightage as per the CBSE Syllabus for Class 11 Chemistry?

The organic chemistry chapter carries more weightage as per the CBSE Syllabus for Class 11 Chemistry.

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