Hydrogen chloride has the chemical formula HCl. It is a colourless gas at ambient temperature that emits white fumes of hydrochloric acid when it comes into contact with air-water vapour. In technology and industry, hydrogen chloride gas and hydrochloric acid are critical. Hydrochloric acid, an aqueous solution of hydrogen chloride, is also known as HCl.

Hydrogen Chloride(HCl)-Preparation, Physical & Chemical Properties, Synthesis, Harmfull Effects, Uses, FAQS

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What is Hydrogen chloride ?

Hydrogen chloride has the chemical formula HCl. It is a colourless gas at ambient temperature that emits white fumes of hydrochloric acid when it comes into contact with air-water vapour. In technology and industry, hydrogen chloride gas and hydrochloric acid are critical. Hydrochloric acid, an aqueous solution of hydrogen chloride, is also known as HCl.

Dissolving gaseous hydrogen chloride in water yields hydrochloric acid. Because of the acid’s corrosive nature, ceramic, glass, or occasionally tantalum apparatus is usually employed. Hydrochloric acid is often sold as a solution containing 28–35 % hydrogen chloride by weight, sometimes known as concentrated hydrochloric acid. Although anhydrous liquid hydrogen chloride is accessible, its application is limited due to the large and expensive containers necessary to store it.

Below mentioned is the structure of HCl:

Hydrogen chloride has the chemical formula HCl. It is a colourless gas at ambient temperature that emits white fumes of hydrochloric acid when it comes into contact with air-water vapour. In technology and industry, hydrogen chloride gas and hydrochloric acid are critical. Hydrochloric acid, an aqueous solution of hydrogen chloride, is also known as HCl.

Structure of HCl

Preparation of HCl

  • Glauber created hydrogen chloride for the first time in 1648 by heating sodium chloride with concentrated H2SO4. Davy demonstrated in 1840 that HCl is a combination of chlorine and hydrogen. Muriatic acid is another term for hydrochloric acid. Warming NaCl crystals with concentrated H2SO4 produces muriatic acid (Sulphuric acid).

NaCl+H2SO4→NaHSO4+HCl

  • As a byproduct, we obtain sodium bisulphate, which is insoluble. As a result, we add additional sodium chloride to it. This mixture must be heated to a higher temperature of around 823K. It produces soluble sodium sulphate and HCl gas. This HCl is dried by treating it with strong sulphuric acid. HCl is not dried in the presence of phosphorus pentoxide or vigorous lime. This is due to the fact that it reacts with both of these molecules.

NaHSO4 + NaCl → Na2SO4 + HCl

  • Typically, the majority of the hydrogen chloride/hydrochloric acid produced is a byproduct of other chemical reactions. The chlorination of hydrocarbons also produces HCl.
  • Dissolving gaseous hydrogen chloride in water yields hydrochloric acid. Because of the acid’s corrosive nature, ceramic, glass, or occasionally tantalum apparatus is usually employed.

Chemical Properties of HCl

  • In an aqueous solution, the chemical dissociates extensively into a hydronium ion (H3O+) and a chloride ion (Cl-).
  • Because it is monoprotic, it can only emit one proton.
  • In water, it can entirely dissociate to generate hydrogen and chloride ions.
  • Noble metals react at a 1:3 ratio with a mixture of nitric acid and hydrochloric acid. This is referred to as aquaregia.
  • The salts of weaker acids react with hydrochloric acid. Sodium carbonate, sodium bicarbonate, and other salts are examples.
  • When hydrochloric acid combines with sodium carbonate and sodium bicarbonate, it produces sodium chloride, carbon dioxide, and water.
  • It also converts sodium sulphate to sodium chloride, sulphur dioxide, and water.
  • Reaction with Sodium Carbonate

Na2CO3 + 2HCl → 2NaCl + CO2↑ + H2O

  • Reaction with Sodium Bicarbonate

NaHCO3 + HCl → NaCl + CO2↑ + H2O

  • Reaction with Sodium Sulphate

Na2SO3 + 2HCl → 2NaCl + SO2↑ + H2O

Physical Properties of HCl

  1. Hydrogen chloride is a colourless, pungent-smelling gas.
  2. The gas smells in damp air due to its high solubility.
  3. Dissociation is essentially complete in dilute liquids. As a result, hydrochloric acid is a powerful acid.
  4. Hydrochloric acid is a hydrogen chloride aqueous solution.
  5. It liquefies at 189K to create a colourless liquid and freezes at159K to form a white solid.
  6. Hydrochloric acid is non-corrosive in the presence of glass.
  7. Hydrochloric acid is extremely corrosive, attacking metals such as platinum, gold, silver, mercury, tantalum, and others.

Organic Synthesis

The industrial manufacture of hydrogen chloride is frequently integrated by creating fluorinated and chlorinated organic chemicals, such as Freon, Teflon, and other CFCs, and chloroacetic acid, PVC, and so on. The manufacture of hydrochloric acid is frequently combined with its captive on-site consumption. In the case of chemical reactions, hydrogen atoms on the hydrocarbon can be replaced by chlorine atoms, and the freed hydrogen atom recombines with the spare atom from the chlorine molecule to form hydrogen chloride. Fluorination is defined as the following reaction of chlorine-replacement that results in the production of hydrogen chloride, with the chemical reaction being as follows:

R−H + Cl2 → R−Cl + HCl

R−Cl + HF → R−F + HCl

The resulting hydrogen chloride can be absorbed in water or reused immediately, yielding industrial or technical grade hydrochloric acid.

Uses of Hydrogen Chloride

  1. Chlorine, aqua regia, and other chlorides are all made using HCl.
  2. It’s used to dissolve noble gases as a solvent.
  3. In laboratories, it is used as a reagent.
  4. Pickling of steel is a procedure that uses weak hydrochloric acid to remove rust or iron oxide from steel or iron before it is processed into wire, sheet and strip coating, and tin mill products.
  5. Organic compound manufacturing: HCl is beneficial in the production of organic compounds such as vinyl chloride and dichloromethane, both of which are used to make PVC. It also manufactures organic substances such as ascorbic acid and pharmaceuticals.
  6. Inorganic compound synthesis: HCl is beneficial in the synthesis of compounds that can be used as water treatment chemicals. Polyaluminium chloride (PAC), ferric acid, and aluminium carbohydrate, for example, are effective in water treatment. It is also beneficial in the regeneration of ion-exchange resins, particularly in the precipitation of cations from the resins.
  7. Gastric Acid: Hydrochloric acid is an essential component of gastric juice in the body, which aids digestion. In the stomach, hydrochloric acid turns inactive pepsinogen into active pepsin, which aids digestion by disrupting the links that link amino acids. This is known as proteolysis. Gastric Acid: Hydrochloric acid is a vital part of gastric juice in the body that helps indigestion. Inactive pepsinogen converts into active pepsin by hydrochloric acid in the stomach which helps digestion by breaking the bonds linking amino acids. This process is Proteolysis.

Harmful effects of HCl

  1. The digestive fluids of the human stomach contain hydrochloric acid.
  2. Excessive acid secretion produces stomach ulcers, whereas a substantial deficit hampers digestion and is sometimes the primary cause of deficiency anaemias.
  3. A few minutes of exposure to 0.1% by volume hydrogen chloride gas in the environment can result in death.
  4. Burns and skin irritation are caused by concentrated hydrochloric acid.

Safety from HCl: When hydrogen chloride comes into touch with water in bodily tissue, it produces caustic hydrochloric acid. Inhaling the fumes can induce coughing, choking, nose, throat, and upper respiratory tract inflammation, and, in severe cases, pulmonary edoema, circulatory system failure, and death. Contact with the skin might result in redness, discomfort, and serious chemical burns. Hydrogen chloride can cause serious eye burns and lasting eye damage.

Sample Questions (FAQs)

Question 1:  Which acid is used in the preparations of hydrogen chloride gas?

Answer:

In the production of Hydrogen Chloride gas, concentrated sulfuric acid is employed.

Question 2: Give two examples of colourless gases that mix to form a white solid.

Answer:

When hydrogen chloride and ammonia combine, they form a white solid.

Question 3: Why can’t dilute hydrochloric acid be concentrated by boiling beyond 22.2%?

Answer:

It cannot be concentrated further than 22.2 percent by boiling because the molecules of dilute hydrochloric acid HCl (g) combine with water vapour.

Question 4: What are the physical properties of hydrogen chloride gas?

Answer:  

  1. It is an odourless and colourless gas.
  2. It has a sour flavour and a strong odour.
  3. It dissolves readily in water and other non-polar solvents.
  4. HCl gas has a boiling point of -83°C and a melting point of -113°C.
  5. It is caustic in nature, causing irritation, pain, and inflammation, as well as coughing, sneezing, and choking sensations when inhaled.

Question 5: How to convert Hydrochloric acid to nascent chlorine? Explain with a balanced equation.

Answer: 

By combining three parts concentrated hydrochloric acid and one part concentrated nitric acid, hydrochloric acid can be transformed to nascent chlorine.

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.

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CBSE Class 11 Chemistry Syllabus

CBSE Class 11 Chemistry Syllabus is a vast which needs a clear understanding of the concepts and topics. Knowing CBSE Class 11 Chemistry syllabus helps students to understand the course structure of Chemistry.

Unit-wise CBSE Class 11 Syllabus for Chemistry

Below is a list of detailed information on each unit for Class 11 Students.

UNIT I – Some Basic Concepts of Chemistry

General Introduction: Importance and scope of Chemistry.

Nature of matter, laws of chemical combination, Dalton’s atomic theory: concept of elements,
atoms and molecules.

Atomic and molecular masses, mole concept and molar mass, percentage composition, empirical and molecular formula, chemical reactions, stoichiometry and calculations based on stoichiometry.

UNIT II – Structure of Atom

Discovery of Electron, Proton and Neutron, atomic number, isotopes and isobars. Thomson’s model and its limitations. Rutherford’s model and its limitations, Bohr’s model and its limitations, concept of shells and subshells, dual nature of matter and light, de Broglie’s relationship, Heisenberg uncertainty principle, concept of orbitals, quantum numbers, shapes of s, p and d orbitals, rules for filling electrons in orbitals – Aufbau principle, Pauli’s exclusion principle and Hund’s rule, electronic configuration of atoms, stability of half-filled and completely filled orbitals.

UNIT III – Classification of Elements and Periodicity in Properties

Significance of classification, brief history of the development of periodic table, modern periodic law and the present form of periodic table, periodic trends in properties of elements -atomic radii, ionic radii, inert gas radii, Ionization enthalpy, electron gain enthalpy, electronegativity, valency. Nomenclature of elements with atomic number greater than 100.

UNIT IV – Chemical Bonding and Molecular Structure

Valence electrons, ionic bond, covalent bond, bond parameters, Lewis structure, polar character of covalent bond, covalent character of ionic bond, valence bond theory, resonance, geometry of covalent molecules, VSEPR theory, concept of hybridization, involving s, p and d orbitals and shapes of some simple molecules, molecular orbital theory of homonuclear diatomic molecules(qualitative idea only), Hydrogen bond.

UNIT V – Chemical Thermodynamics

Concepts of System and types of systems, surroundings, work, heat, energy, extensive and intensive properties, state functions. First law of thermodynamics – internal energy and enthalpy, measurement of U and H, Hess’s law of constant heat summation, enthalpy of bond dissociation, combustion, formation, atomization, sublimation, phase transition, ionization, solution and dilution. Second law of Thermodynamics (brief introduction)
Introduction of entropy as a state function, Gibb’s energy change for spontaneous and nonspontaneous processes.
Third law of thermodynamics (brief introduction).

UNIT VI – Equilibrium

Equilibrium in physical and chemical processes, dynamic nature of equilibrium, law of mass action, equilibrium constant, factors affecting equilibrium – Le Chatelier’s principle, ionic equilibrium- ionization of acids and bases, strong and weak electrolytes, degree of ionization,
ionization of poly basic acids, acid strength, concept of pH, hydrolysis of salts (elementary idea), buffer solution, Henderson Equation, solubility product, common ion effect (with illustrative examples).

UNIT VII – Redox Reactions

Concept of oxidation and reduction, redox reactions, oxidation number, balancing redox reactions, in terms of loss and gain of electrons and change in oxidation number, applications of redox reactions.

UNIT VIII – Organic Chemistry: Some basic Principles and Techniques

General introduction, classification and IUPAC nomenclature of organic compounds. Electronic displacements in a covalent bond: inductive effect, electromeric effect, resonance and hyper conjugation. Homolytic and heterolytic fission of a covalent bond: free radicals, carbocations, carbanions, electrophiles and nucleophiles, types of organic reactions.

UNIT IX – Hydrocarbons

Classification of Hydrocarbons
Aliphatic Hydrocarbons:
Alkanes – Nomenclature, isomerism, conformation (ethane only), physical properties, chemical reactions.
Alkenes – Nomenclature, structure of double bond (ethene), geometrical isomerism, physical properties, methods of preparation, chemical reactions: addition of hydrogen, halogen, water, hydrogen halides (Markovnikov’s addition and peroxide effect), ozonolysis, oxidation, mechanism of electrophilic addition.
Alkynes – Nomenclature, structure of triple bond (ethyne), physical properties, methods of preparation, chemical reactions: acidic character of alkynes, addition reaction of – hydrogen, halogens, hydrogen halides and water.

Aromatic Hydrocarbons:

Introduction, IUPAC nomenclature, benzene: resonance, aromaticity, chemical properties: mechanism of electrophilic substitution. Nitration, sulphonation, halogenation, Friedel Craft’s alkylation and acylation, directive influence of functional group in monosubstituted benzene. Carcinogenicity and toxicity.

To know the CBSE Syllabus for all the classes from 1 to 12, visit the Syllabus page of CBSE. Meanwhile, to get the Practical Syllabus of Class 11 Chemistry, read on to find out more about the syllabus and related information in this page.

CBSE Class 11 Chemistry Practical Syllabus with Marking Scheme

In Chemistry subject, practical also plays a vital role in improving their academic scores in the subject. The overall weightage of Chemistry practical mentioned in the CBSE Class 11 Chemistry syllabus is 30 marks. So, students must try their best to score well in practicals along with theory. It will help in increasing their overall academic score.

CBSE Class 11 Chemistry Practical Syllabus

The experiments will be conducted under the supervision of subject teacher. CBSE Chemistry Practicals is for 30 marks. This contribute to the overall practical marks for the subject.

The table below consists of evaluation scheme of practical exams.

Evaluation SchemeMarks
Volumetric Analysis08
Salt Analysis08
Content Based Experiment06
Project Work04
Class record and viva04
Total30

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 the approval of the teacher.

Practical Examination for Visually Impaired Students of Class 11

Below is a list of practicals for the visually impaired students.

A. List of apparatus for identification for assessment in practicals (All experiments)
Beaker, tripod stand, wire gauze, glass rod, funnel, filter paper, Bunsen burner, test tube, test tube stand,
dropper, test tube holder, ignition tube, china dish, tongs, standard flask, pipette, burette, conical flask, clamp
stand, dropper, wash bottle
• Odour detection in qualitative analysis
• Procedure/Setup of the apparatus

B. List of Experiments A. Characterization and Purification of Chemical Substances
1. Crystallization of an impure sample of any one of the following: copper sulphate, benzoic acid
B. Experiments based on pH
1. Determination of pH of some solutions obtained from fruit juices, solutions of known and varied
concentrations of acids, bases and salts using pH paper
2. Comparing the pH of solutions of strong and weak acids of same concentration.

C. Chemical Equilibrium
1. Study the shift in equilibrium between ferric ions and thiocyanate ions by increasing/decreasing
the concentration of eitherions.
2. Study the shift in equilibrium between [Co(H2O)6]2+ and chloride ions by changing the
concentration of either of the ions.

D. Quantitative estimation
1. Preparation of standard solution of oxalic acid.
2. Determination of molarity of a given solution of sodium hydroxide by titrating it against standard
solution of oxalic acid.

E. Qualitative Analysis
1. Determination of one anion and one cation in a given salt
2. Cations – NH+4
Anions – (CO3)2-, S2-, (SO3)2-, Cl-, CH3COO-
(Note: insoluble salts excluded)
3. Detection of Nitrogen in the given organic compound.
4. Detection of Halogen in the given organic compound.

Note: The above practicals may be carried out in an experiential manner rather than recording observations.

We hope students must have found this information on CBSE Syllabus useful for their studying Chemistry. Learn Maths & Science in interactive and fun loving ways with ANAND CLASSES (A School Of Competitions) App/Tablet.

Frequently Asked Questions on CBSE Class 11 Chemistry Syllabus

Q1

How many units are in the CBSE Class 11 Chemistry Syllabus?

There are 9 units in the CBSE Class 11 Chemistry Syllabus. Students can access various study materials for the chapters mentioned in this article for free at ANAND CLASSES (A School Of Competitions).

Q2

What is the total marks for practicals examination as per the CBSE Class 11 Chemistry Syllabus?

The total marks for the practicals as per the CBSE Class 11 Chemistry Syllabus is 30. It includes volumetric analysis, content-based experiment, salt analysis, class record, project work and viva.

Q3

Which chapter carries more weightage as per the CBSE Syllabus for Class 11 Chemistry?

The organic chemistry chapter carries more weightage as per the CBSE Syllabus for Class 11 Chemistry.

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