LEARNING GUIDE
Week No.: _1_
TOPIC/S
Scope of Inorganic Chemistry 2
History and Discovery of Hydrochloric Acid
Manufacture of Hydrochloric Acid
Physical and Chemical Properties of Hydrochloric Acid
Uses and Applications of Hydrochloric Acid
EXPECTED COMPETENCIES
At the end of the lesson, students must be able to:
1. outline the history of hydrochloric acid;
2. discuss how hydrochloric acid is manufactured by Mannheim process;
3. identify the physical, chemical properties, uses and applications of hydrochloric acid
and
4. make use of the Safety Data Sheet when handling hydrochloric acid.
CONTENT
Scope of Inorganic Chemistry 2 (taken from the original Course Syllabus for CHT 223A)
Learning Plan:
Wk.
No.
1
2
3
Learning
Outcomes
LO1, LO2,
LO3
LO1, LO2,
LO3
LO3
Content/ Topic
Mission, Vision, Goals and
ChET Program Educational
Objectives and Program
Outcomes, TUP Quality Policy,
Class room policy.
Hydrochloric Acid
a. Properties
b. Uses
c. Methods of manufacture
Methodology &
Strategy
Assessment
Tools
Traditional lecture
Use of models
Group discussions
Recitation
of TUPV
Mission and
Vision
Power point
presentation
Sulfuric Acid
a. Properties
b. Uses
c. Methods of manufacture
Power point
presentation
Nitric Acid and Ammonia
a. Properties
b. Uses
Lecture/
Discussion Power point
presentation
Quiz
Seat work
Laboratory
report
Quiz
Laboratory
report
Quiz
Seat work
c. Methods of manufacture
4
5
6
7-8
9
1011
1213
14
LO4
LO1, LO2,
LO3, LO4
Cement
a. Definition
b. Types of Cement
c. Portland cement
d. Composition of Portland
cement
e. Types of Portland cement
f. Manufacture of Portland
cement
LO5
LO6
Concrete and Aggregates
a. Definition of concrete
b. Types of concrete
c. Components of concrete
d. Concrete mixing
e. Curing of concrete
f. Properties of concrete
LO7
LO8, LO9
LO6, LO7,
LO8, LO9
Lecture Discussion
Power point
presentation
PRE-LIM EXAM
Testings of Portland Cement
a. Physical tests
b. Chemical tests
c. Significance of tests
LO5, LO6
Output
Exercises
MIDTERM EXAM
Testings of Aggregates
a. Physical tests
b. Chemical tests
c. Significance of tests
Glass
a. Definition
b. Composition of glass
c. Types of glass
d. Manufacture of glass
END-TERM EXAM
Written Exam
Lecture Discussion
Power point
presentation
Lecture
Discussion
PPT
Quiz
Seat work
Output
Exercises
Objective
questions,
problem
solving and
essay
questions
Quiz
Laboratory
report
Quiz
Seat work
Video presentation
Laboratory
report
Written Exam
Objective
questions,
problem
solving and
essay
questions
Lecture
Discussion
PPT
Video presentation
Lecture
Discussion
PPT
Written Exam
Quiz
Laboratory
report
Quiz
Laboratory
report
Objective
questions,
essay
questions
Introduction
Figure 1.1 Hydrochloric Acid
(Source: https://www.chemistryworld.com/podcasts/hydrochloric-acid/3005801.article)
This powerful acid, an aquatic solution of hydrogen chloride, has been known
for a long time. The acid's early names have a rather nautical flavor, reflecting the
production of the acid from common salt. The alchemists would have called it 'spirits
of salt' while its common name before modern conventions came in was muriatic acid,
where 'muriatic' was a fancy term for briny.
History
➢ The old (pre-systematic) name muriatic acid has the same origin (muriatic means
"pertaining to brine or salt", hence muriate means hydrochloride), and this name is still
sometimes used.
➢ The name hydrochloric acid was coined by the French chemist Joseph Louis GayLussac in 1814.
➢ Hydrochloric acid was known to European alchemists as spirits of salt or acidum
salis (salt acid).
➢ Gaseous HCl was called marine acid air.
➢ Hydrochloric acid has been an important and frequently used chemical from early
history and was discovered by the alchemist Jabir ibn Hayyan around the ear 800 AD.
➢ Aqua regia, a mixture consisting of hydrochloric and nitric acids, prepared by
dissolving sal ammoniac in nitric acid, was described in the works of Pseudo-Geber, a
13th-century European alchemist. Other references suggest that the first mention of
aqua regia is in Byzantine manuscripts dating to the end of the 13th century.
➢ Free hydrochloric acid was first formally described in the 16th century by Libavius,
who prepared it by heating salt in clay crucibles.
➢ Other authors claim that pure hydrochloric acid was first discovered by the
German Benedictine monk Basil Valentine in the 15th century, when he
heated common salt and green vitriol, whereas others argue that there is no clear
reference to the preparation of pure hydrochloric acid until the end of the 16th century.
➢ In the 17th century, Johann Rudolf Glauber from Karlstadt Main, Germany used
sodium chloride salt and sulfuric acid for the preparation of sodium sulfate in the
Mannheim process, releasing hydrogen chloride gas. Joseph Priestley of Leeds,
England prepared pure hydrogen chloride in 1772, and by 1808 Humphry Davy of
Penzance, England had proved that the chemical composition included hydrogen and
chlorine.
➢ During the Industrial Revolution in Europe, demand for alkaline substances increased.
A new industrial process developed by Nicolas Leblanc of Issoudun, France enabled
cheap large-scale production of sodium carbonate (soda ash). In this Leblanc process,
common salt is converted to soda ash, using sulfuric acid, limestone, and coal, releasing
hydrogen chloride as a by-product.
➢ The Industrial Revolution, now also known as the First Industrial Revolution, was the
transition to new manufacturing processes in Europe and the United States, in the
period from about 1760 to sometime between 1820 and 1840. This transition included
going
from hand
production
methods to machines,
new chemical
manufacturing and iron production processes, the increasing use of steam
power and water power, the development of machine tools and the rise of
the mechanized factory system.
➢ Until the British Alkali Act 1863 and similar legislation in other countries, the excess
HCl was vented into the air. After the passage of the act, soda ash producers were
obliged to absorb the waste gas in water, producing hydrochloric acid on an industrial
scale.
➢ In the 20th century, the Leblanc process was effectively replaced by the Solvay
process without a hydrochloric acid by-product. Since hydrochloric acid was already
fully settled as an important chemical in numerous applications, the commercial interest
initiated other production methods, some of which are still used today. After the year
2000, hydrochloric acid is mostly made by absorbing by-product hydrogen chloride
from industrial organic compounds production
➢ Since 1988, hydrochloric acid has been listed as a Table II precursor under the
1988 United Nations Convention Against Illicit Traffic in Narcotic Drugs and
Psychotropic Substances because of its use in the production of heroin, cocaine,
and methamphetamine.
Production
The Mannheim process is an industrial process for the production of hydrogen
chloride and sodium sulfate from sulfuric acid and sodium chloride. The Mannheim furnace is
also used to produce potassium sulfate from potassium chloride. The Mannheim process is a
stage in the Leblanc process for the production of sodium carbonate.
Figure 1.2 Manufacture of Hydrochloric Acid using a Manheim Type of Furnace
(Source: https://www.daviddarling.info/encyclopedia/H/hydrochloric_acid.html)
In all manufacturing processes for hydrochloric acid another useful product is obtained
along with the acid. In the process illustrated in Figure 1.2, using a Mannheim type
furnace, sodium sulfate is produced.
Key to Figure 1.2
1) Common salt is added to the furnace.
2) Sulfuric acid inlet by way of a lead-lined tank.
3) Rotating shaft.
4) Rotating stirrers mix reactants.
5) Reaction chamber. The salt and sulfuric acid react to form sodium sulfate and
hydrochloric acid, which comes off as the gas hydrogen chloride because of the high
temperature.
6) Oil burner heats reaction chamber.
7) Combustion gases outlet.
8) Salt cake (sodium sulfate) outlet.
9) Hydrogen chloride gas led off.
10) Hydrogen chloride gas piped into the absorption column below the packed
section.
11) The absorption chamber is packed with Raschig rings made of glass. On the
surface of these rings the hydrogen chloride combines with water, emitted at the top
of the tower (12) to form hydrochloric acid. This reaction releases heat.
12) Water inlet. The water passes down the packed column and dissolves the hydrogen
chloride gas.
13) Cooling water inlet.
14) Cooling water outlet.
15) Hot concentrated hydrochloric acid passes into the cooler at the bottom of the
column.
16) Cooling water inlet.
17) Cooling water outlet.
18) Cool hydrochloric acid led out to storage tanks.
19) Spent gas vent.
 The process is conducted in a Mannheim furnace, a large cast iron kiln. Sodium
chloride and sulfuric acid are first fed onto a stationary reaction plate where an initial
reaction takes place. The stationary plate is up to 6 m (20 ft) in diameter. Rotating
rabble arms constantly turn over the mixture and move the intermediate product to a
lower plate.
 The kiln portion of the furnace is constructed with bricks that have high resistance to
direct flame, temperature, and acid. The other parts of the furnace are heat and acid
resistant. Hot flue gas passes up over the plates carrying out liberated hydrogen
chloride gas.
 The intermediate product reacts with more sodium chloride in the lower, hotter section
of the kiln producing sodium sulfate. This exits the furnace and passes through cooling
drums before being milled, screened and sent to product storage facilities.
 The process involves intermediate formation of sodium bisulfate, an exothermic
reaction that occur at room temperature:
NaCl + H2SO4 → HCl + NaHSO4
The second step of the process is endothermic, requiring energy input:
NaCl + NaHSO4 → HCl + Na2SO4
Temperatures in the range 600-700 °C are required.
Physical Properties
 Physical properties of hydrochloric acid, such as boiling and melting points, density,
and pH, depend on the concentration or molarity of HCl in the aqueous solution. They
range from those of water at very low concentrations approaching 0% HCl to values for
fuming hydrochloric acid at over 40% HCl.
Chemical Properties
 Hydrochloric acid (HCl) is a clear, colorless, fuming, poisonous, highly acidic, aqueous
solution of hydrogen chloride, HCl.
 A saturated solution of hydrochloric contains about 43% HCl and gives a constantboiling mixture.
 It is an extremely corrosive mineral acid and must be handled in glass or plastic
equipment or in apparatus using special alloys (tantalum, nickel-molybdenum).
 Hydrochloric acid is a strong acid, since it is completely dissociated in water. It can
therefore be used to prepare salts containing the Cl– anion called chlorides.
 Of the six common strong mineral acids in chemistry, hydrochloric acid is the
monoprotic acid least likely to undergo an interfering oxidation-reduction reaction.
 It is one of the least hazardous strong acids to handle; despite its acidity, it consists of
the non-reactive and non-toxic chloride ion. Intermediate-strength hydrochloric acid
solutions are quite stable upon storage, maintaining their concentrations over time.
These attributes, plus the fact that it is available as a pure reagent, make hydrochloric
acid an excellent acidifying reagent.
 Hydrochloric acid is frequently used in chemical analysis to prepare ("digest") samples
for analysis. Concentrated hydrochloric acid dissolves many metals and forms oxidized
metal chlorides and hydrogen gas.
 It also reacts with basic compounds such as calcium carbonate or copper(II) oxide,
forming the dissolved chlorides that can be analyzed.
Grades of Hydrochloric Acid
 Hydrochloric acid is produced in solutions up to 38% HCl (concentrated grade). Higher
concentrations up to just over 40% are chemically possible, but the evaporation rate is
then so high that storage and handling require extra precautions, such as pressurization
and cooling.
 Bulk industrial-grade is therefore 30% to 35%, optimized to balance transport
efficiency and product loss through evaporation.
 In the United States, solutions of between 20% and 32% are sold as muriatic acid.
 Solutions for household purposes in the US, mostly cleaning, are typically 10% to 12%,
with strong recommendations to dilute before use.
 In the United Kingdom, where it is sold as "Spirits of Salt" for domestic cleaning, the
potency is the same as the US industrial grade.
 In other countries, such as Italy, hydrochloric acid for domestic or industrial cleaning
is sold as "Acido Muriatico", and its concentration ranges from 5% to 32%.
Uses and Applications
Hydrochloric acid is used across many industries for a variety of applications and may
be the most-known inorganic acid. HCl is an important industrial and commercial acid that is
employed in food-industry productions, oil recovery, metal refining, ore processing, chemical
production, and cleaning products. Hydrochloric acid is versatile and employed across various
operations. Its strong acidic nature, stability, low health hazard, low reactivity, and catalytic
capabilities contribute to HCl’s usefulness and versatility
a) Pickling of Steel
One of the most important applications of hydrochloric acid is in the pickling of steel,
to remove rust or iron oxide scale from iron or steel before subsequent processing, such
as extrusion, rolling, galvanizing, and other techniques. Technical quality HCl at typically 18%
concentration is the most commonly used pickling agent for the pickling of carbon steel grades.
Fe2O3 + Fe +6 HCl  3FeCl2 + 3 H2O
The steel pickling industry has developed hydrochloric acid regeneration processes, such as the
spray roaster or the fluidized bed HCl regeneration process, which allow the recovery of HCl
from spent pickling liquor. The most common regeneration process is the pyrohydrolysis
process, applying the following formula:
4 FeCl3+ 4 H2O +O2  8 HCl + 2 Fe2O3
b) Production of Organic Compounds:
Another major use of hydrochloric acid is in the production of organic compounds, such
as vinyl chloride and dichloroethane for PVC. This is often captive use, consuming locally
produced hydrochloric acid that never actually reaches the open market.
Other organic compounds
produced
with
hydrochloric
acid
include bisphenol
A for polycarbonate, activated
carbon,
and ascorbic
acid,
as
well
as
numerous pharmaceutical products.
2H2C=CH2 + 4 HCl +O2  2 ClCH2CH2Cl + 2H2O
(dichloroethane by oxychlorination)
c) Production of Inorganic Compounds:
Numerous products can be produced with hydrochloric acid in normal acid-base
reactions, resulting in inorganic compounds. These include water treatment chemicals such
as iron(III) chloride and polyaluminium chloride (PAC).
Fe2O3+ 6 HCl  2 FeCl3 + 3 H20
(iron(III) chloride from magnetite)
Both iron(III) chloride and PAC are used as flocculation and coagulation agents in sewage
treatment, drinking water production, and paper production. Other inorganic compounds
produced with hydrochloric acid include road application salt calcium chloride, nickel(II)
chloride for electroplating,
and zinc
chloride for
the galvanizing industry
and battery production.
CaCO3 + 2 HCl  CaCl2 + CO2 + H2O
(calcium chloride from limestone)
d) Regeneration of Ion Exchangers:
High-quality hydrochloric acid is used in the regeneration of ion exchange
resins. Cation
exchange is
widely
used
to
remove ions such
as
Na+ and
Ca2+ from aqueous solutions, producing demineralized water. The acid is used to rinse the
cations from the resins. Na+ is replaced with H+ and Ca2+ with 2 H+.
(Ion exchangers and demineralized water are used in all chemical industries, drinking water
production, and many food industries.
e) pH Control and Neutralization:
Hydrochloric acid can be used to regulate the acidity (pH) of solutions.
OH- + HCl  H2+ ClIn industry demanding purity (food, pharmaceutical, drinking water), high-quality hydrochloric
acid is used to control the pH of process water streams. In less-demanding industry, technical
quality hydrochloric acid suffices for neutralizing waste streams and swimming pool pH
control.
f) Food Industry:
The largest percentage of the food industry’s HCl use is in high-fructose corn syrup
production. HCl is used as an “acid-enzyme” in product synthesis reactions to acidify a
cornstarch solution and begin carbohydrate breakdown. Muriatic acid is also utilized in the
manufacture of aspartame, gelatin, fructose, citric acid, and hydrolyzed vegetable protein.
g) Other Applications:
The pharmaceutical industry sees significant hydrochloric acid utilization through
chemical syntheses designed to form HCl-salts of active pharmaceutical components, allowing
what would be an otherwise insoluble drug product to become soluble in the human body and
perform its designed function.
Hydrochloric acid is also used in the production of fertilizers, dyes, and cleaning
products. HCl has a function in tin and tantalum ore refining, in producing nickel(II) chloride
for electroplating applications and in generating zinc chloride for galvanized steel. HCl
regenerates ion-exchange resins by replacing built-up cations with hydrogen ions, which
rejuvenates the exchange resin, re-enabling it for further use.
The following pie graph as well as application-excerpts from PubCHEM provide some
insight into HCl categories and example applications.
Interesting Facts About Hydrochloric Acid
➢ Humans have known about hydrochloric acid for a long time. Originally produced from
green vitriol and rock salt, and later a combination of sulfuric acid and common salt,
it’s also known as muriatic acid, acidum salis, and spirits of salt.
➢ HCl is one of the strongest chemicals commercially available within cleaners.
➢ Annually, the world produces at least 20 million tons of hydrochloric acid.
➢ Hydrochloric acid appears in the human body as an integral component in the digestive
system. It occurs naturally within the digestive gastric juices present in many animal
stomachs, including humans.
Safety
➢ Due to its highly corrosive nature, great care must be taken when handling hydrochloric
acid.
➢ Skin contact can result in serious burns, while inhalation can irritate the respiratory
tract.
➢ Swallowing this type of acid can corrode mucous membranes, stomach, and esophageal
tissues.
➢ Long-term exposure for people working with hydrochloric acid can result in chronic
health conditions like dermatitis, bronchitis, and photosensitization.
➢ Safety protocol has been established in conjunction with this acid in its industrial and
domestic uses so that humans may employ it for its benefits without being harmed in
the process.
➢ In laboratories, it is advisable to apply a barrier cream to the hands prior to use.
➢ Keep it away from any heat source such as burners, ovens, sunlight etc.
➢ Keep containers closed and in an upright position when not in use.
➢ For dilute HCl add the acid to water and store the diluted acid solution in a reagent
bottle (never add the water to the acid).
➢ On industrial scale, label the product, chemical name and chemical formula. Name the
ingredients and formulation details where relevant.
➢ Follow the first aid and emergency procedures. Provide the details of manufacturer,
reference to Safety Data Sheet (SDS) and expiry date.
Click the link below for the Safety Data Sheet (SDS) of Hydrochloric Acid:
https://pubchem.ncbi.nlm.nih.gov/compound/Hydrochloric-acid#section=Safety-andHazards&fullscreen=true
PROGRESS CHECK
Note:
Progress check will be posted on NEOLMS and must be answered once you are informed
of the schedule. The Progress check will serve as your assessment for the particular week/s.
REFERENCES
Brown, T. L., Jr., H. E., Bursten, B. E., Murphy, C., Woodward, P., Langford, S., Sagatys, D.,
& George, A. (2013). Chemistry: The central science. Pearson Higher Education AU.
Mortimer, Charles E. (1986). Chemistry 6th Edition, National Bookstore, Inc.
http://worldofchemicalsmedia.blogspot.com/2013/12/interesting-facts-abouthydrochloric.html