Organic chemistry is a branch of science that studies the structure, properties, and interactions of organic compounds having covalent carbon bonds. By examining their structure, their structural formula can be derived. To better understand their behavior, physical and chemical properties, as well as chemical reactivity, are investigated. The study of organic processes includes the chemical synthesis of natural products, pharmaceuticals, and polymers, as well as laboratory and theoretical (in silico) studies of individual organic molecules.
Organic chemistry studies hydrocarbons (compounds comprising only carbon and hydrogen) and compounds based on carbon but also includes other elements such as oxygen, nitrogen, sulphur, phosphorus (present in many biochemicals), and the halogens. The study of compounds containing organometallic elements is known as organometallic chemistry.
Table of Contents
Qualitative Analysis of Organic Compounds
After organic compounds have been synthesized in their purest form, qualitative analysis is used to identify their structure and characterization. The analysis provides insight into the constituents that make up the chemical. Carbon, hydrogen, oxygen, and nitrogen (in some cases) are the most prevalent components found in organic molecules, hence they are detected through analysis. Sulfur, halogens, metals, and phosphorus are occasionally found and detected via qualitative analysis.
Detection of Carbon and Hydrogen
Principle
Dry copper (II) oxide or cupric oxide can be used to detect carbon and hydrogen in an organic molecule. In a hard glass tube, the organic compound is heated with dry copper (II) oxide. The compound’s carbon will be oxidized to carbon dioxide, while the hydrogen will be oxidized to water. The following are the reactions:
C + 2CuOΔ → CO2 + 2Cu
2H + 2CuOΔ → HO2 + 2Cu
For example, if the organic chemical under test has the molecular formula CxHy, then its full combustion in the presence of cupric oxide can be stated as:
The ability of carbon dioxide to render lime water milky can be used to detect it (Calcium Carbonate is formed). The ability of water to condense on the cool sections of the test tube can be used to identify it. Anhydrous copper sulfate becomes ‘blue’ as a result of this reaction.
Ca(OH)2 + CO2 → CaCO3 + H2O
CuSO4 + 5H2O → CuSO4 ⋅ 5H2O
Procedure
A small amount of the dry and pure organic component is mixed with about 5-6 times the weight of dry and pure cupric oxide powder in the laboratory. The combination is then heated to a high temperature in a rigid test tube with a delivery tube. The delivery tube has a bulb in the middle and is dipped into the lime water on the other end, as depicted.
Glass wool and anhydrous copper sulfate are put into the delivery tube’s bulb. When carbon is heated, it is oxidized to carbon dioxide, turning the lime water milky. The anhydrous copper sulfate on the bulb becomes blue when hydrogen in the organic chemical is oxidized to water, indicating its presence.
Detection of Nitrogen
Nitrogen is found in some organic molecules, such as amines and nitro compounds. A set of experiments are used to detect nitrogen in various organic molecules, as follows:
Dry heating test: It confirms the presence of nitrogen when the organic component under examination is intensely heated and generates a burnt hair or feather odor. However, the test has limits because many nitrogen-containing substances do not generate odor.
Soda-lime test: In a dry test tube, a little amount of organic substance is heated vigorously with soda lime (NaOH+CaO). The presence of nitrogen is indicated if the vapors smell like ammonia.
NH2CONH2 + 2NaOHCaO, Δ → 2NH3 + Na2CO3
However, these assays have limitations, like many organic compounds with Nitro and Azo (–N=N–) groups do not show up in this test.
Lassaigne’s test: Lassaigne’s test is used to detect nitrogen, halogens, and sulfur in an organic compound. This is one of the most reliable tests used to detect these components. The elements present in the organic compounds are fused with sodium metal to convert them from covalent to their ionic form.
Preparing Lassaigne’s extract: In a fusion tube, a little amount of sodium is heated vigorously until it forms a globule. The tube is removed from the flame once the globule has formed, and a little amount of organic chemical is added to the tube, which is then heated vigorously until the tube turns red hot. Meanwhile, prepare a China dish with 10-15 mL of water. When the tube becomes red hot, it is dipped into a water-filled China dish and filtered. The resulting filtrate is known as the Sodium Fusion Extract or Lassaigne’s Extract.
Testing for Nitrogen element: Because the sodium in the extract combines with the excess water to generate sodium hydroxide, the sodium fusion extract is alkaline. To keep the solution alkaline, sodium hydroxide is sometimes added. To this alkaline solution of Sodium fusion extract, a freshly made ferrous sulfate (FeSO4) is added. The mixture is then slightly warmed before being chilled. To acidify the solution, a small amount of dilute sulfuric acid is added. If there is nitrogen in the solution, it will turn green or blue. The presence of nitrogen and sulfur in the organic component is indicated by the solution turning blood-red.
The reactions for the above test are as follows:
During the fusion process, the carbon and nitrogen in the organic component combine to generate sodium cyanide, as shown:
Na + C + N → NaCN
When sodium ferrocyanide or sodium hexacyanoferrate (II) is heated with ferrous sulfate solution, some of the Fe2+ or ferrous ions are oxidized to ferric (Fe3+) ions. Prussian blue is produced when ferric ions combine with sodium hexacyanoferrate (II) to yield Iron (II) hexacyanoferrate (II) or ferric ferrocyanide.
2NaCN + FeSO4 → Na2SO4 + Fe(CN)2
Fe(CN)2 + 4NaCN → Na4[Fe(CN)6] Sodiumhexacyanoferrate (ii)
3Na4[Fe(CN)6] + 4Fe3+ → Fe4[Fe(CN)6]3
Detection of Halogens
The halogens, if present in the organic compound, can be detected using the following tests:
Beilstein’s Test: Beilstein’s test for detecting halogens in organic compounds is a simple, sensitive, and effective method. A clean and stout copper wire is heated in the Bunsen burner’s non-luminous flame until the flame’s bluish-green or greenish color fades. After that, the wire is immersed in the organic compound and exposed to the flame once more. The creation of cupric halides, and hence the presence of halogen in the compound, is indicated by the flame turning bluish-green or green. Even molecules like urea and thiourea, for example, display this test due to the creation of volatile cupric cyanide, which has some restrictions. It also doesn’t say what kind of halogens are present in the chemical (bromine, chlorine, or iodine).
Lassaigne’s Test: It is an extremely accurate assay for detecting halogens in organic compounds. The preparation of Sodium Fusion Extract or Lassaigne’s Extract is the first stage. The halogens in organic compounds are transformed to sodium halides in the following way:
Na + X → NaX
The next step is to boil a portion of the extract in weak nitric acid and then strain the solution. A few drops of silver nitrate solution are added to this and the following precipitates are tested:
Chlorine is indicated by the formation of a white precipitate that is soluble in ammonia but insoluble in dilute HNO3.
The presence of bromine is indicated by the formation of a pale-yellow precipitate that is somewhat soluble in ammonia.
The presence of iodine is indicated by the formation of a yellow precipitate that is insoluble in ammonia.
Detection of Sulphur
Sulfur, present in an organic compound can be detected using the following tests:
Lassaigne’s Test: When a sulfur-containing organic component is fused with sodium, the resulting extract contains sodium sulfide.
2Na + S → Na2S
The presence of sulfur in the chemical will be confirmed by the following tests:
Sodium Nitroprusside Test: If a small amount of sodium fusion extract is treated with a few drops of sodium nitroprusside, the compound will turn violet, indicating that it contains sulfur. Standing still causes the violet color to fade slowly.
Na2S + Na4[Fe(CN)5(NO)] → Na4[Fe(CN)5(NOS)]
Lead Acetate Test: Dilute acetic acid is added to the second half of the portion to acidify it, followed by a few drops of lead acetate. The presence of sulfur in the organic compound is established if a dark precipitate indicating the development of lead sulfide is observed.
Na2 S + (CH3COO)2 Pb → PbS + 2CH3COONa
Detection of Phosphorus
By fusing the organic compound with sodium peroxide, an oxidizing agent, the presence of phosphorus in the organic component can be determined. The organic compound’s phosphorus is oxidized to sodium phosphate.
5Na2O2 + 2PΔ → 2Na3PO4 + 2Na2O
Water is used to remove the fused material, and the resulting aqueous solution is subsequently heated with strong nitric acid. Ammonium molybdate is added to this. The presence of phosphorus is indicated by a yellow precipitate or color (due to the production of ammonium phosphomolybdate).
Detection of Oxygen
While there are no direct tests for detecting the presence of oxygen in an organic substance, the procedures listed below can establish its existence indirectly
The presence of functional groups or tests to confirm the presence of functional groups such as −OH,−COOH,−NO2, etc., indicates the presence of oxygen indirectly.
When the sum percentages of components in an organic molecule determined by quantitative analysis do not equal 100 %, the differential sum indicates the presence of oxygen, and its proportion can be calculated.
Sample Problems
Question 1: What is qualitative analysis for organic compounds and why it is important?
Answer
Organic compound qualitative analysis is a non-quantifiable analysis of organic compounds. It’s significant since it provides a detailed account of the elements found in organic molecules.
Question 2: Which steps are used in the qualitative analysis of organic compounds?
Answer
For different elements such as oxygen, nitrogen, carbon and hydrogen, sulphur, phosphorus, and halogens, qualitative analysis employs various methods of detection or tests. Each of these tests has its own set of instructions to follow and must be completed independently.
Question 3: Which method is used for the detection of Nitrogen in an organic compound?
Answer
Three separate tests are used to detect nitrogen: the dry heating test, the soda lime test, and Lassaigne’s test.
Question 4: How can we detect the presence of sulfur in an organic compound?
Answer
Sulphur can be detected by utilising Lassaigne’s extract and treating it with either sodium nitroprusside or lead acetate and acetic acid to produce a violet coloration or a yellow precipitate or coloration.
Question 5: What are the types of qualitative analysis?
Answer
Individual constituents in an organic complex can be detected through qualitative analysis. Each element has its own set of tests that are used to validate that it is present in the organic complex under examination.
Question 6: How oxygen is being detected?
Answer
The existence of functional groups or tests to validate the presence of functional groups (such as OH, COOH, NO2, etc.) indirectly implies the presence of oxygen.
The differential sum reveals the existence of oxygen, and its proportion may be computed, when the total percentages of components in an organic molecule determined by quantitative analysis do not equal 100%.
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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