The p-block, which spans groups 13 to 18, is located on the right side of the normal periodic table. Their electrical configuration is ns2 np1–6 in general. Despite being the first element in group 18, helium is not part of the p-block. Except for the first row, each row in the table has six p-elements.
The only block with all three categories of elements: metals, nonmetals, and metalloids is this one. On a group-by-group basis, the p-block elements are group 13, icosagens; 14, crystallogens; 15, pnictogens; 16, chalcogens; 17, halogens; and 18, the helium group, which includes noble gases (except helium) and oganesson. The p-block can also be defined as including post-transition metals, metalloids, reactive nonmetals, such as halogens, and noble gases.
Table of Contents
Sulphur Dioxide
When sulphur-containing materials, such as metal, are heated, such as when smelting metal or burning coal or oil, sulphur dioxide is produced as a waste gas. It is a significant contaminant that is presently seen as a threat to the environment.
Structure of Sulphur Dioxide
The polar covalent connections between the sulphur atom and two oxygen atoms give sulphur dioxide its twisted structure. SO2 is the chemical formula for sulphur dioxide. Sulphur dioxide contains sp2 hybridised sulphur. The bond angle should ideally be 120°, whereas the O–S–O bond angle is 119°. The lone pair of electrons on the Sulphur atom cause this. The bond angle is reduced from 120° to 119° due to the lone pair-bond pair repulsion.
A sigma (σ) and (π) connection connects each oxygen atom in the Sulphur dioxide molecule to the Sulphur atom. The sp2–p overlap forms the σ bonds between Sulphur and Oxygen atoms, whereas one of the π links is created by pπ–pπ overlap and the other by pπ–dπ overlap.
The electronic configuration of S is 1s22s22p63s23p4.
One electron from the 3p orbital moves to the 3d orbital during the synthesis of SO2, and S undergoes sp2 hybridization. Two of these orbitals have sigma bonds with two oxygen atoms, whereas the third has a single pair. Each of the p-orbital and d-orbital electrons are unpaired. One electron makes a pπ–pπ link with one oxygen atom, while the other forms a pπ–dπ bond with the other. This is why SO2 has a bent structure with a 143 pm bond length.
Due to resonance, however, both S–O bonds are identical.
Preparation of Sulphur Dioxide
Sulphur dioxide and traces of sulphur trioxide (6–8%) are generated when sulphur is burned in the air.
S(s)+O2(g) → SO2(g)
Laboratory Preparation of Sulphur Dioxide- Sulphur dioxide is made in the lab by reacting sulphites with dilute sulphuric acid. This process also produces sodium sulphate and water as byproducts.
Na2SO3(s)+H2SO4(aq) → SO2(g)+Na2SO4(aq)+H2O(l)
Copper turnings are gently heated in a flask with strong sulfuric acid to produce sulphur dioxide.
Cu(s)+2H2SO4(aq)→SO2(g)+CuSO4(aq)+2H2O(l)
Industrial Preparation of Sulphur Dioxide- Sulphur dioxide is generated commercially as a byproduct of roasting sulphide ores like Iron Pyrites or Zinc blend.
4FeS2(s)+11O2(aq)→2Fe2O3(s)+8SO2(g)
Physical Properties of Sulphur Dioxide
Sulphur dioxide is a colourless, poisonous gas with a terrible, stifling odour.
It has a lower density than air and is easily soluble in water. At 0°C, one volume of water may dissolve approximately eight litres of gas.
It is easily liquefied at ambient temperature and at 2 atm pressure.
It has a boiling temperature of 263K and a freezing point of 197.8 K.
It’s a non-flammable gas that serves as a solvent for phosphorus, sulphur, and iodine, among other things.
Chemical Properties of Sulphur Dioxide
Acidic Character of Sulphur Dioxide- Sulphur dioxide reacts with water to generate sulphurous acid. Its acidic aqueous solution turns blue litmus crimson. As a result, SO2 is classified as a sulphurous acid anhydride.
SO2(g)+H2O(l)→H2SO3(aq)
Sulphur dioxide quickly combines with sodium hydroxide solution to produce sodium sulphite, which then reacts with additional sulphur dioxide to produce sodium hydrogen sulphite.
2NaOH(aq)+SO2(g)→Na2SO3(aq)+H2O(l)
Na2SO3(aq)+H2O(l)+SO2(g)→2NaHSO3(aq)
The solution turns milky when sulphur dioxide gas is bubbled through lime water. The milkiness goes away when you pass too much sulphur dioxide gas because calcium bisulphite forms.
Ca(OH)2(aq)+SO2(g)→CaSO3(aq)+H2O(l)
CaSO3(aq)+H2O(l)+SO2(g)→Ca(HSO3)2(aq)
Combination with Oxygen- When sulphur dioxide is heated, it interacts with oxygen to generate sulphur trioxide.
This reaction takes place in the presence of catalysts such as platinized asbestos, vanadium pentoxide, and others. When sulphur dioxide is heated, it interacts with oxygen to generate sulphur trioxide.
Reaction with Halogens- Sulphur dioxide becomes sulphuryl fluoride, chloride, and bromide when it reacts directly with the halogens (fluorine, chlorine, and bromine). For example, In the presence of charcoal, SO2 reacts with chlorine to form sulphuryl chloride. The reaction is aided by the use of charcoal as a catalyst.
SO2(g)+Cl2(g)→SO2Cl2(l)
As an Oxidising Agent- SO2 oxidises powerful reducing agents like H2S, HI, Mg, Fe, etc., and itself gets reduced to sulphur or sulphide.
SO2(g)+2H2S(g)→2H2O(l)+3S
SO2 as a Reducing Agent- Aqueous SO2 shows a reducing character and itself gets oxidised to H2SO4.
Acidified orange potassium dichromate solution is reduced to light green chromium sulphate.
K2Cr2O7+H2SO4+3SO2→K2SO4+Cr2(SO4)3+H2O
It lowers the acidified potassium permanganate solution, releasing the pink colour of KMnO4.
2KMnO4+5SO2+2H2O → K2SO4+2MnSO4+2H2SO4
As a Bleaching Agent- In the presence of moisture, SO2 functions as a bleaching agent. It may bleach coloured wool, silk, flowers, and hair, among other things. The bleaching effect of sulphur dioxide is accounted for by the creation of nascent hydrogen, which converts the colouring ingredient to a colourless reduced result.
SO2+2H2O → H2SO4+2[H]
SO2‘s bleaching effect is quite transient. Due to oxidation by air, the bleached colourless chemical will gradually recover its original colour standing in the air.
Test of Sulphur Dioxide
The existence of this gas can be detected by reducing an acidified potassium permanganate solution. The pink colour of KMnO4 is released, indicating that sulphur dioxide gas is present.
2KMnO4+5SO2+2H2O → K2SO4+2MnSO4+2H2SO4
Uses for Sulphur Dioxide
Sulphur dioxide is the main component of sulphuric acid, one of the most widely used chemicals on the planet.
It is used to make a variety of sulphites, including sodium hydrogen sulphite, calcium hydrogen sulphite, and others. These sulphites are used to keep jams, pickles, and jellies fresh.
Sulphur dioxide is a common pesticide that may also be used to sterilise materials like wood or straw.
It kills insects and other pests by acting as a fumigating agent.
It’s used to refine petroleum and sugar, as well as bleach sensitive fabrics like wool.
Sulphur dioxide is also employed as an antichlor or a substance that removes excess chlorine from bleached materials.
A variety of organic and inorganic compounds are dissolved using liquid SO2.
It’s also utilised to keep things cool.
Sample Questions (FAQs)
Question 1: How does Sulphur dioxide form acid rain?
Answer:
When molecules like sulphur dioxide and nitrogen oxides are released into the air, a chemical reaction occurs, resulting in acid rain. Sulfuric and nitric acids are formed when these substances combine with water, oxygen, and other chemicals. Acid rain is formed when these acids fall to the earth.
Question 2: What are the uses of sulphur dioxide?
Answer:
Sulfur dioxide is the primary component of sulfuric acid, which is one of the world’s most commonly used chemicals.
It’s utilised to create sulphites like sodium hydrogen sulphite and calcium hydrogen sulphite, among other things. Sulphites are employed to preserve the freshness of jams, pickles, and jellies.
Sulfur dioxide is a widely used insecticide that may also be used to sterilise materials such as wood or straw.
It acts as a fumigating agent, killing insects and other pests.
It’s utilised in the refinement of petroleum and sugar, as well as the bleaching of delicate materials such as wool.
Antichlor, or a chemical that eliminates excess chlorine from bleached materials, is also used with sulphur dioxide.
Question 3: What are the physical properties of sulphur dioxide?
Answer:
Sulphur dioxide is a colourless, toxic gas having a foul, suffocating odour.
Its density is lower than that of air, and it is easily soluble in water. One litre of gas may be dissolved in one litre of water at 0°C.
At 2 atm pressure and ambient temperature, it is quickly liquefied.
It has a boiling point of 263K and a freezing point of 197.8K .
It’s a non-flammable gas that may be used to dissolve phosphorus, sulphur, and iodine, among other substances.
Question 4: What will happen when sulphur dioxide reacts with chlorine?
Answer:
Sulphuryl chloride is formed when SO2 interacts with chlorine in the presence of charcoal. The use of charcoal as a catalyst aids the process.
SO2(g) + Cl2 (g) → SO2Cl2 (l)
Question 5: What will happen when sulphur dioxide reacts with sodium hydroxide?
Answer:
Sulphur dioxide reacts fast with sodium hydroxide solution to form sodium sulphite, which is then combined with more sulphur dioxide to form sodium hydrogen sulphite.
2NaOH (aq) + SO2 (g) → Na2SO3 (aq) + H2O(l)
Na2SO3 (aq) + H2O (l) + SO2 (g) → 2NaHSO3 (aq)
Question 6: What is the confirmatory test to detect the presence of Sulphur dioxide gas?
Answer
The existence of this gas can be detected by reducing an acidified potassium permanganate solution. The pink colour of KMnO4 is released, indicating that sulphur dioxide gas is present.
2KMnO4+5SO2+2H2O → K2SO4+2MnSO4+2H2SO4
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 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‐ , S2‐, NO2‐ , SO32‐, SO2‐ , NO ‐ , Cl‐ , Br‐, I‐, PO43‐ , 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 theapproval 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.
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