Avogadro’s number is critical to understanding the structure of molecules as well as their interactions and combinations. e.g. because one atom of oxygen will combine with two atoms of hydrogen to form one molecule of water (H2O), one mole of oxygen (6.022 × 1023 of O atoms) will mix with two moles of hydrogen (2 × 6.022 × 1023 of H atoms) to form one mole of H2O.
Table of Contents
Another feature of Avogadro’s number is that the mass of one mole of material equals the molecular weight of that substance. Water, for example, has a mean molecular weight of 18.015 a.m.u. implying that one mole of water weighs 18.015 grams. Many chemical computations are made easier by this feature.
Now let’s discuss some important concepts before understanding the gram atomic mass and gram molecular mass.
Atomic Mass: Atomic mass is the mass of an atom of the given element. The unit of atomic mass is a.m.u. often denoted as u. One atomic mass unit (a.m.u.) is said to be exactly equal to the 1/12 the ratio of the mass of 1 mole of C-12 atoms to Avogadro’s Constant (NA).
Molecular Mass: Molecular Mass is the sum of the mass of the atoms present in a molecule of the given substance. Its unit is also a.m.u. e.g. the molecular mass of NH3 = 14 + 1 × 3 = 17 a.m.u.
Molar Mass: The mass of the 1 mole of a given substance is known as molar mass. The SI unit of molar mass is kg/mol however g/mol is the usually used unit. Molar mass can also be defined as the molecular mass of the given substance expressed in grams. e.g. 2 a.m.u. is the molecular mass of hydrogen gas therefore as per the definition the molar mass of hydrogen gas will be 2 g.
Mole Concept: It is a concept revolving around 12 g of C-12 isotope containing atoms equal to Avogadro’s Constant. Mole is actually an amount. The amount can be of atoms, molecules, ions, electrons, fruits, or books but our scope would be limited to chemical entities. What we actually do is calculate the mass of chemical entities in terms of mole. The value of Avogadro’s Constant i.e. the value of 1 mole of a substance is 6.0221367 × 1023.
Mole: One mole is defined as the amount of the substance which contains as many entities as there are atoms in 12 g of C-12 isotope. As measured by mass spectrometer the mass of one atom of C-12 atom is found to be 1.992648 × 10-23 g. Since 1 mole of C-12 atoms is 12g. Therefore, the number of atoms present in 1 mole = 12g / 1.992648*10-23 g atom-1 or 6.0221367 × 1023 atoms. The value of 1 mole is known as Avogadro’s Constant. The term ‘Avogadro’s Constant’ is termed after the great pioneer Amedeo Avogadro. It is denoted by the symbol NA.
Gram Atomic Mass
Gram atomic mass is the periodic table element’s atomic weight in grams. The molar mass of an element is the mass of one mole in grams. The mass of one mole of an element is defined as its gram atomic mass.
It is calculated by taking an element’s atomic weight from the periodic table and converting it to grams. Thus, when the mass of an element is expressed in grams then it is known as gram atomic mass. For example, the gram atomic mass of helium is 4 g. Similarly, sodium (Na) has an atomic weight of 22.99 u and a gram atomic mass of 22.99 grams. So one mole of sodium atoms weighs 22.99 g. This implies that the quantity of the element of the given substance when weighs equal to its gram atomic mass is called one gram atom.
The gram atomic mass of a material is the amount of that substance in grams that is numerically equivalent to its atomic mass. If we wish to write a substance’s gram atomic mass, we first write its atomic mass, then subtract the atomic mass unit u and add grams to the numerical value of the atomic mass. That is,
Mass of the element (in g) = Number of gram atoms / Atomic mass of the element (in g)
Gram Molecular Mass
The mass in grams of one mole of a molecular material is known as the gram molecular mass. The molar mass and gram molecular mass are the same things. The main distinction is that gram molecular mass defines the mass unit. The gram molecular mass (g/mol) can be expressed in grams or grams per mole (g/mol).
How to find the Gram Molecular Mass?
To determine the mass, use the molecular formula.
Look up each element’s relative atomic mass in the formula.
Multiply the subscript following each element symbol (the number of atoms) by the atomic mass of that element. If there is no subscript, it implies that the molecule contains only one atom of that element.
To get the gram molecular mass, add all of the numbers together.
The gram molecular mass of a substance is the amount of that substance in grams that is numerically equivalent to its molecular mass. To write a substance’s gram molecular mass, first, write its molecular mass, then subtract the molecular mass unit u and add grams to the numerical value of the molecular mass. For example, the gram molecular mass of oxygen gas (O2) is 32 g.
Number of gram molecules = Mass of the substance (in g) / Molecular mass of the substance (in g)
The mass of one molecule of material in grams should not be confused with the mass of one molecule of the substance in grams. The real mass or molecular mass of a material is the mass of one molecule.
Sample Problems
Problem 1: What is Avogadro’s Constant?
Solution:
Avogadro’s number is critical to understanding the structure of molecules as well as their interactions and combinations. e.g. because one atom of oxygen will combine with two atoms of hydrogen to form one molecule of water (H2O), one mole of oxygen (6.022 × 1023 of O atoms) will mix with two moles of hydrogen (2 × 6.022 × 1023 of H atoms) to form one mole of H2O.
Problem 2: Why are the gram atomic mass and gram molecular mass of all elemental substances are same?
Solution:
The mass of a grams of a molecule. a mass in grams equal to a substance’s molecular weight or the sum of all the atomic weights in its molecular formula
The mass in grams of one mole of atoms in a monatomic chemical element is known as gram atomic mass. It is the same as the relative atomic mass (or atomic weight) in grams. Only Nobel gases exist in a monotonic state. Hence, the gram atomic mass and gram molecular mass of all elemental substances are same.
Problem 3: Calculate the number of atoms present in 4 moles of hydrogen gas.
Solution:
1 molecule of hydrogen gas has 2 atoms
1 mole of hydrogen gas has NA molecules ⇒ 1 mole of hydrogen gas has 2 × NA atoms
Therefore, 4 moles hydrogen gas has 4 × 2 × NA atoms i.e. 8 × NA atoms
Problem 4: What is a mole?
Solution:
A mole is the unit of amount of substance. The number of entities present in a mole is equal to Avogadro’s Constant. Mole is the former term used for the term ‘ one gram atom’.
Problem 5: How many moles of oxygen gas are required to produce 3 moles of CO2?
Solution:
Chemical reaction for the formation of carbon dioxide is
C +O2 ⇢ CO2
The above equation is balanced. Hence we can say that
1 mole of carbon and 1 mole of oxygen gas combine to form 1 mole of carbon dioxide.
Therefore, for the formation of 3 moles of carbon dioxide there will be requirement of 3 moles of oxygen gas.
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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