Thermodynamics is a field of physics that studies the relationship between heat, work, and temperature, as well as their relationships with energy, entropy, and the physical properties of matter and radiation.
The four principles of thermodynamics regulate the behaviour of these quantities, which provide a quantitative description using quantifiable macroscopic physical quantities but may be described in terms of microscopic elements using statistical mechanics.
Thermodynamics is a branch of science and engineering that covers a vast range of topics, including physical chemistry, biochemistry, chemical engineering, and mechanical engineering, as well as other complex fields like meteorology.
Table of Contents
Enthalpies of Different Types of Reactions
The enthalpy of a system is the product of its internal energy and the product of its pressure and volume. It’s also referred to as heat content. That is to say,
H = E + PV
Where,
E = Internal energy of the system
P = Pressure of the system
V = Volume of the system
The absolute value of enthalpy cannot be calculated because it is a state function. On the other hand, a change in enthalpy (ΔH) associated with a process may be measured precisely and is supplied by the formula.
ΔH = Hproducts – Hreactants
= Hp – Hr
If ΔV is the change in volume in a reaction at constant temperature and pressure, the change in enthalpy will equal the sum of the internal energy change (ΔE) and the work done in expansion or contraction. That is correct.
ΔH = ΔE + P × ΔV
Enthalpy or enthalpy changes accompanying chemical processes are expressed in a variety of ways, depending on the nature of the reaction. These will be explored further down.
Enthalpy of Formation
The enthalpy of formation is the change in enthalpy that occurs when one mole of a compound is made from its constituent parts. ΔHf is the symbol for it. For example, the enthalpy of production of ferrous sulphide and acetylene can be expressed as:
Fe(s) + S(s) → FeS(s) ΔHf = –100.41kJmol–1
2C(s) + H2(g) → C2H2(g) ΔHf = 222.3kJmol–1
Standard Enthalpy of Formation
The standard enthalpy of production of a compound is defined as the enthalpy change that occurs when one mole of a compound is created from its elements when all components are in their standard states (298k and 1 atm pressure). ΔH∘f is the symbol for it. By convention, the standard enthalpy of production of all elements in their standard state is taken to be zero.
Standard Enthalpy of Reaction from Standard Enthalpy of Formation
We can calculate the reaction enthalpy under standard conditions using the values of standard enthalpies of the formation of various reactants and products. The standard enthalpy of reaction is equal to the product formation enthalpy minus the reactant formation enthalpy.
ΔH∘ = [Total standard heat of formation of products] – [Total standard heat of formation of reactants]
ΔH∘ = ΔH∘f (products) – ΔH∘f (reactants)
Let us consider a general reaction:
aA + bB → cC + dD
The standard enthalpy of reaction is given by
ΔH∘ = ΔH∘f (products) – ΔH∘f (reactants)
= – [a × ΔH∘f(A) + b × ΔH∘f(B)]
Enthalpy of Combustion
The enthalpy of combustion is the change in a system’s enthalpy when one mole of a substance is completely burnt in excess of air or oxygen. ΔHc is the symbol for it. The enthalpy of methane combustion is seen in the following reaction:
Enthalpy changes are prevalent when a material is dissolved in a solvent. When a reaction occurs in a solution, the enthalpy of the solution of reactants and products must be addressed. The enthalpy of solution is the change in enthalpy that occurs when one mole of a substance is dissolved in a specific amount of solvent at a specific temperature.
When one mole of copper sulphate is dissolved in water to generate one molar solution, the enthalpy absorbed is 78.5kJ/mol. If the solution is diluted more, the enthalpy will change again. We will reach a point where further dilution has no thermal effect if we continue to dilute the fluid. This circumstance is known as the state of endless dilution. To avoid including the quantity of the solvent in our definition, we must incorporate the concept of infinite dilution, which can be stated as follows: The change in enthalpy that occurs when one mole of a chemical is dissolved in a solvent so that further dilution has no effect on the enthalpy. The enthalpy of a solution can also be expressed as :
KCl(s) + H2O(l) → KCl(aq) ΔH = –18.4kJmol–1
MgSO4(s) + H2O(l) → MgSO4(aq) ΔH = –84.8kJmol–1
Enthalpy of Neutralisation
The enthalpy of neutralisation is the change in a system’s enthalpy when one gram equivalent of an acid is neutralised by one gram equivalent of a base or vice versa in dilute solution. The enthalpy of neutralisation can be demonstrated using the example below.
According to the data, the enthalpy of neutralisation of a strong acid and strong base is –57.1kJmol–1, regardless of which acid or base is utilised. This pattern has been properly described using ionisation theory. We get HA and BOH when we mix equivalent amounts of any strong acid and base in a dilute solution.
Ignoring the ions which are present on both sides of the equation, we get
H+(aq)+OH–(aq)→H2O(l) ΔH = –57.1kJmol–1
The enthalpy of neutralising acid and a base is thus the same as the enthalpy of producing water from hydrogen and hydroxyl ions. When weak acids or weak bases are neutralised by strong bases or strong acids, the enthalpy of neutralisation varies substantially from –57.1kJmol–1.
Enthalpy of Hydration
The enthalpy of hydration is defined as the change in enthalpy that occurs when one mole of anhydrous salt is combined with the requisite number of moles of water to generate hydrated salt.
Enthalpy of Fusion
Enthalpy of fusion is the change in enthalpy that occurs when one mole of a solid substance is converted into a liquid state at its melting point. Consider the melting of one mole of ice at its melting point of 0∘C or 273∘F. The following is a description of the procedure:
H2Oice(s)→H2OWater(l) ΔH=6.0kJmol–1
During this procedure, a total of 6.0kJmol–1 of enthalpy is absorbed. The magnitudes of intermolecular forces between different substances can be compared using their fusion values. As the enthalpy of fusion of a substance increases, so does the amount of intermolecular forces.
Enthalpy of Vaporisation
This process consumes a total of 6.0kJmol–1 of enthalpy. Based on the fusion values of different substances, we can compare the magnitudes of intermolecular forces between them. As the enthalpy of fusion of a substance rises, so does the amount of intermolecular forces.
H2OWater(l)→H2Osteam(g) ΔH=40.6kJmol–1
Enthalpy of Sublimation
Sublimation is the transformation of a solid into a gaseous state without becoming liquid first. It occurs at a temperature below the melting point of the solid. Enthalpy of sublimation is the change in enthalpy that occurs when one mole of a solid is directly converted into a gaseous state at a temperature below its melting point. The sublimation enthalpy of iodine, for example, is 62.4kJmol–1. It’s possible to write it as:
I2(s) → I2(g) ΔH = 62.4kJmol–1
Enthalpy of Transition
The enthalpy of transition is the change in enthalpy that occurs when one mole of an element changes from one allotropic state to another. For example, the transformation of diamond into amorphous carbon might be illustrated as
Cdiamond→Camorphous ΔH = 13.8kJmol–1
Bond Enthalpy
The establishment of a bond between two atoms causes energy to be released. The same quantity of energy is absorbed when the link is severed. The average amount of energy required to break all bonds of a certain type in one mole of a substance is known as bond energy.
As a result, the H-H bond’s bond energy is equal to the energy required to break all of the bonds in a single mole of gas. It is expressed in terms of kcal/mol or kJ/mol. The H-H bond, for example, has a bond energy of 433 kJ/mol–1 or 103.58 kcal/mol–1. The following are the bond energies of several common bonds:
Bond
Bond Energy
Cl–Cl
243 kJmol–1
O–O
499.0 kJmol–1
C–H
414.0 kJmol–1
O–H
460.0 kJmol–1
Sample Questions
Question 1: What is enthalpy, and what are its types?
Answer
The sum of a system’s internal energy and the product of its pressure and volume is called enthalpy. The absolute value of enthalpy cannot be established because it is a function of the state. On the other hand, a change in enthalpy (H) associated with a process can be precisely measured. Enthalpy or enthalpy changes accompanying chemical reactions are stated in a variety of ways depending on the nature of the reaction, such as Enthalpy of Formation, Enthalpy of Combustion, and Enthalpy of Neutralization.
Question 2: What are various types of enthalpies?
Answer
The following are some of the most common types of enthalpies:
Enthalpy of Formation
Enthalpy of Combustion
Enthalpy of Solution
Enthalpy of Neutralisation
Enthalpy of Hydration
Enthalpy of Fusion
Enthalpy of Vaporisation
Enthalpy of Sublimation
Enthalpy of Transition
Bond Enthalpy
Question 3: From the standard enthalpy of formation, how can we compute the standard enthalpy of reaction?
Answer
The standard enthalpy of reaction can be calculated using the standard enthalpy of formation of various reactants and products. The standard enthalpy of reaction is equal to the product formation enthalpy minus the reactant formation enthalpy.
ΔH∘ = [Total standard heat of formation of products] – [Total standard heat of formation of reactants]
ΔH∘ = ΔH∘f(products) – ΔH∘f(reactants)
Let us consider a general reaction:
aA+bB→cC+dD
The standard enthalpy of reaction is given by
ΔH° = ΔH°f(products) – ΔH°f(reactants)
= – [a×ΔH∘f (A)+b×ΔH∘f (B)]
Question 4: What is the enthalpy of neutralisation?
Answer
The enthalpy of neutralisation is the change in a system’s enthalpy when one gram equivalent of an acid is neutralised by one gram equivalent of a base or vice versa in dilute solution. The enthalpy of neutralising an acid and a base is the same as the enthalpy of producing water from hydrogen and hydroxyl ions. When weak acids or weak bases are neutralised by strong bases or strong acids, the enthalpy of neutralisation differs significantly from 57.1kJmol–1.
Question 5: What is bond enthalpy?
Answer
The release of energy is caused by the establishment of a bond between two atoms. A same quantity of energy is absorbed when a link is severed. The bond energy is the average amount of energy required to break all of a substance’s bonds of a particular type in one mole. As a result, the H-H bond’s bond energy is the energy required to break all of the bonds in a single mole of gas. It is expressed in either kcal/mol or kJ/mol units. The H-H bond, for example, has a bond energy of 433 kJ/mol–1 (103.58 kcal/mol–1).
Question 6: What is enthalpy of vaporisation ?
Answer
The enthalpy of vaporisation is the enthalpy shift that occurs when one mole of liquid is turned into a vapour or gaseous state at its boiling point. The enthalpy absorbed when one mole of water is converted to steam at 100°C is 40.6 kJmol–1, which is the enthalpy of water vaporisation. The following is how the process works:
H2OWater(l) → H2Osteam(g) ΔH = 40.6 kJmol–1
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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