Hydrogen peroxide is one of the most common chemical substances that we come across in our daily lives. It is found in hair bleaching and medical products. In this lesson, we will dive deeper into learning what hydrogen peroxide actually is, including its structure, properties and more.

Hydrogen peroxide is a chemical compound containing molecules of hydrogen and water. Its chemical formula is written as H₂O₂. When hydrogen peroxide is in its pure form, it is usually seen as a clear liquid with a slight pale blue colouration. It has a higher viscosity than water. However, it is a thermodynamically unstable liquid that tends to decompose when subjected to light. This chemical is also found in the human body.

Table of Contents

IUPAC Name	Hydrogen Peroxide
Chemical Formula	H2O2
Molar Mass	34.0147 g/mol
Density	1.45 g/cm³
Melting Point	-0.43 °C
Boiling Point	150.2 °C

Structure of H₂O₂

It has a non-planar open book (skew) structure. The 0-H bond length is 95 pm, and O-O bond length is 147•5 pm. The H-O-O bond angle is 94•8, and the dihedral angle (angle between the planes containing the H-O-O group) is 111.5° in the gas phase. The bond lengths and angles are slightly changed in liquid and solid phases due to hydrogen bonding. The bond angle between the two planes reduces to 90•2° in the crystalline state.

The structure of H₂O₂ can also be explained on the basis of valence bond theory, where both oxygen atoms are sp-hybridised. Two of these hybrid orbitals on each oxygen are occupied by lone pairs of electrons. The third hybrid orbital overlaps with the s-orbital of a hydrogen atom to form an O-H sigma bond, while the fourth one forms a sigma bond with the half-filled hybrid orbital of the second oxygen atom.

Chemical Properties of H₂O₂

1. It decomposes rapidly on heating in the presence of finely divided metals, such as Cu, Au, Ag, Ca, Fe, Pt, MnO₂, carbon, alkali oxides, dust and light.

H₂O₂ + H₂O₂ → 2 H₂O + O₂

∆H = -196 kJ

This constitutes an example of auto-oxidation and auto-reduction. One molecule of H₂O₂ (O.N. of O–1) is oxidised to O2 (0.N.-0), while the other is reduced to H2O (O.N.–2).

2. It is diamagnetic and exhibits dipole moment 2.1 D.

3. It is dense (density 1-4 g/cm³), has a higher b.p. (425 K) and is more viscous than water. This is because H₂0₂ is more highly associated with hydrogen bonding than water. Oxidation and reduction by H₂O₂ in the acidic medium are generally slow, while it is rapid in an alkaline medium.

4. It acts as a weak acid (dissociation constant 1.55 x 1012 at 293 K) and forms two series of salts, i.e., hydroperoxides (acidic salts) and peroxides (normal salts).

H₂O₂ ⇔ H⁺ + HO₂^–

H₂O₂ ⇔ H⁺ + O₂^²-

It neutralises alkalis and carbonates.

5. Hydrogen peroxide is a strong oxidising agent in both acidic and basic media.

H₂O₂ + H⁺ +2e- → 2H₂O (Acidic medium)

H₂O₂ + OH^– +2e- → 3H₂O (Basic medium)

6. Hydrogen peroxide is a reducing agent in the presence of a strong oxidising agent in both alkali and acidic media, and importantly, oxygen is released every time.

H₂O₂ → 2H⁺ + 2e- + O₂ (Acidic medium)

H₂O₂ + 2OH^– → 3H₂O + 2e- +O₂ (Basic medium)

7. Hydrogen peroxide acts as a bleaching agent due to the oxidation of colouring matter by nascent oxygen.

H₂O₂ → 2 H₂O + O

Colouring matter + O = Colourless matter

Hydrogen Peroxide Preparation

Merck’s Method

By the action of dilute acids on sodium peroxide.

Na₂O₂ + H₂SO₄ → Na₂SO₄+ H2O₂ (30%)

Laboratory Method

The action of dilute acids on barium peroxide.

BaO₂8H2O + H₂SO₄ → BaSO₄+ H₂O₂ + 8 H₂O

In this method, anhydrous BaO₂ cannot be used since the precipitated BaSO₄ forms a protective layer around unreacted BaO_2, thereby preventing further reaction.

By Bubbling CO₂ through a Paste of BaO₂

BaO₂ +H₂O+ CO₂ → BaCO₃+ H₂O₂

By the Electrolysis of 50% H₂SO₄ (Manufacture of H₂0₂)

Electrolysis of a 50 per cent solution of sulphuric acid is done using Pt as the anode and graphite as the cathode. The reactions taking place are as follows:

2H₂SO₄→ 2H⁺+2 HSO₄^–

At cathode:

2H⁺+2e→H2

At anode:

2HSO₄^– → H₂S₂O₈ + 2e

Peroxodisulphuric acid is distilled with water under reduced pressure when low boiling H₂O₂ distils over along with water leaving behind high boiling H₂SO₄.

In a modification of the above method, an equimolar mixture of H₂SO₄ and ammonium sulphate can also be taken as an electrolyte to give a more concentrated solution of hydrogen peroxide.

By Auto Oxidation of 2-Ethyl Anthraquinone (10% solution in benzene and cyclohexane)

Air is bubbled through the solution to get H₂O₂ and 2-ethyl anthraquinone, which is reduced by H₂ in the presence of a Pd catalyst to give back 2-ethyl anthraquinone.

Concentration of H₂O₂

• Dilute H₂O₂ is concentrated to about 50% by slow evaporation on a water bath. It is further concentrated to 90% in a vacuum desiccator using concentrated H₂SO₄ as a dehydrating agent.
• Further, a concentration of 99% is obtained by distillation under reduced pressure. The last traces of moisture in 99% H₂O₂ are removed, or anhydrous H₂O₂ is obtained by cooling it to 263 K in a cold bath of ether and dry ice, followed by sending a few crystals of solid H₂O₂.
• When needle-shaped crystals of 100 per cent H₂0₂ separate out, these crystals are removed, dried and melted to get pure H₂O₂.

H₂O₂ Storage

H₂O₂ is not stored in glass bottles since the alkali oxides present in glass tend to catalyse its decomposition. It is, therefore, stored in Teflon bottles or paraffin wax-coated plastic bottles. Small amounts of acid, glycerol, alcohol, acetanilide and H₃PO₄ are often used as stabilisers to check its decomposition.

Hydrogen Peroxide Uses

Depending on its concentration level, hydrogen peroxide has a wide range of applications. Some of the popular ones are listed below.

• Hydrogen peroxide is an important chemical that is used in the treatment of domestic and industrial effluents.
• It is used in pulp and paper bleaching.
• It is used in detergents.
• It is used for waste-water treatment.
• It is used for disinfecting wounds.
• High-concentration H₂O₂ is used as a propellant.

Solved Questions

1. Hydrogen peroxide that is moist cannot be dried over concentrated H₂SO₄ because

(a) It can catch fire

(b) It is reduced by H₂SO₄

(c) It is oxidised by H₂SO₄

(d) It decomposes H₂SO₄

Answer: C

2. Hydrogen peroxide molecules are

(a) Monatomic and form X₂^2- ions

(b) Diatomic and form X₂^–, ions

(c) Diatomic and form X^– ions

(d) Monoatomic and form X^– ions.

Answer: C

3. Decomposition of H₂0₂ is favoured by

(a) Traces of acids

(b) alcohol

(c) Acetanilide

(d) MnO

Answer: D

4. 30 volumes of H₂O₂ means

(a) 30% H₂O₂ solution

(b) 30 cm³ of the solution contains 1 g of H₂O₂

(c) 1 cm³ of the solution liberates 30 cm³ of O₂ at STP

(d) 30 cm³ of the solution contains 1 mole of H₂O₂

Answer: C

5. The O-O-H bond angle in H₂O₂ is

(a)106°

(b) 109•28°

(c) 120°

(d) 97°

Answer: D

6. The oxide that gives H₂O₂ on treatment with dilute acid is

(a) PbO₂

(b) Na₂0₂

(c) MnO₂

(d) TiO₂

Answer: B

7. In an aqueous solution, hydrogen peroxide oxidises H₂S into

(a) Sulphur

(c) Caro’s acid

(b) Sulphuric acid

(d) Marshall’s acid

Answer: A

8. For making H₂O₂ in the laboratory

(a) MnO₂ is added to dilute cold H₃PO₄

(b) BaO₂ is added to CO₂ bubbling through cold water

(c) PbO₂ is added to an acidified solution of KMnO₄

(d) Na₂O₂ is added to boiling water

Answer: B

9. HCI is added to the following oxides. Which one will give H₂O₂?

(a) MnO₂

(b) PbO₂

(c) BaO

(d) None of the above

Answer: D

10. Which one of the following statements regarding hydrogen peroxide is false?

(a) It is a strong oxidising as well as a reducing agent in acidic as well as the basic medium

(b) It is decomposed by MnO₂

(c) It is more stable in a basic solution

(d) It behaves as a reducing agent towards acidified KMnO

Answer: C

11. The hair dyes available in the market generally contain two bottles, one containing dye and the other hydrogen peroxide. Before applying the dye, the two solutions are mixed. The hydrogen peroxide,

(a) Is added to dilute the solution of the dye

(b) Oxidises the dye to give the desired colour

(c) Reduces the dye to give the desired colour

(d) Acidifies the solution of the dye

Answer: B

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.

...

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.

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

Q1

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).

Q2

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.

Q3

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.