Inorganic Commodity Chemicals
HYDROCHLORIC ACID
ChE 313 Industrial Chemistry Lecture
Engr. May V. Tampus
Hydrochloric Acid: interesting facts
Found naturally in the gases evolvedfrom volcanoes
Present in the atmosphere of theplanet Venus
Present in the digestive system ofmost mammals
Listed as one of the prohibitedsubstance
Hydrochloric Acid Production
*Data source: Kirk-Othmer Encyclopedia of Chemical Technology
Today worldwide usage of HCl exceeds 20 M tons annually.
Industrial Uses of HCl
Descaling agent
Catalyst in food processing
Pickling liquor to dissolve mill scales in steel industry
Dissolve pulverized stone during petroleum operation –oil-well acidiIng
CaCl2 manufacture
Oil & gas well acidizing
Production of high-fructose corn syrup (HFCS)
Manufacture of dyes, phenols, & plastics
pH control and neutralization
Regenerant of ion-exchange
resins
Gelatin manufacture
Soy sauce production
Magnesia and metal
production
Manufacture of chemical
intermediates, e.g., FeCl3,
ZnCl2, Al2Cl3, etc.
Ore reduction (Mn, Ra, V, Ta,
Sn, W)
Leather processing
Hydrochloric Acid
Forms of Hydrochloric Acid
Hydrogen chloride: gas at ordinarytemperature
Hydrochloric acid: aqueous solutionof hydrogen chloride
Muriatic acid: commercial grade ofHCl solution; clear colorless to slightlyyellow liquid with a strong pungentand irritating odor; strong and highlycorrosive; soluble in water and alcoholbut insoluble in hydrocarbon
Common Grades of Muriatic Acid
Mass %HCl
Density
Specific gravity O Be
27.92 1.1417 18
31.45 1.1600 20
35.21 1.1789 22
Industrial Grades of HCl
1) Concentrated grade – 38-40%
2) Bulk-industrial grade – 30-34%
(optimized for transport & limit product
loss)
3) Household grade – 10-12% (intended for
cleaning)
Physical Properties of Hydrochloric Acid
Properties Value
Molar mass 36.46 g/mol
Melting point -114.8o C
Boiling point -84.9oC
Specific gravity 1.84
Solubility in water 720 g/L (at 20o C)
Vapor pressure 423 kPa
pKa -7
pKb 21.0
NFPA ratings Health: 3 Flammability: 0 Reactivity: 1 Other: ACID
Stability Stable under ordinary conditions
Thermochemistry of HCl
Thermodynamic Properties
Std enthalpy of formation ΔfH
o298
–92.31 kJ mol-1
Std enthalpy of combustion ΔcH
o298
–95.31 kJ mol-1
Standard molar entropy So
298
186.902 J K-1 mol-1
Specific heat capacity, C 0.7981 J K-1 g-
Chemical Properties of Hydrochloric Acid
• Hydrochloric acid readily ionizes in water:
HCl (g) + H2O(l) Cl-(aq) + H3O+(aq)
• Even in the absence of water it still reacts as an acid to form:
HCl (g) + CH3OH (l) Cl-(aq) +
CH3O+H2(aq)
Industrial Production of Hydrochloric Acid
Direct Synthesis from hydrogen
and chlorine
Decomposition of metal chlorides
by acids
As by-product from chemical
processes
Recovery by incineration of waste
organics
Recovery from hydrochloric acid
solutions
Synthesis from Hydrogen and Chlorine
• Less than 10% of HCl in U.S.is made via this reaction
• Reaction is adiabatic andtakes place in an HCl burneror HCl oven
• Acid produced is calledBURNER ACID
)44(1842 )()(2)(2 kcalkJHClClH ggg
Synthesis from Hydrogen and Chlorine
• PROCESS CONDITIONSTemperature: 2490o CPressure: 14 kPaRapid cooling of free
H2 & Cl2 to 200o CEquilibrium mixture contains 4.2% v/v
free Cl2
Use a stoichiometric amount of feed gas mixture in order to produce 99% HCl 30-32% HCl (burner acid) is produced
by absorption
Decomposition of Metal Chlorides by Acids
1. Salt-Sulfuric Acid (Saltcake) Process
NaCl + H2SO4 HCl + NaHSO4 at 150oC (1)
NaCl + NaHSO4 HCl + Na2SO4 at 550-660o C (2)
Both reactions are endothermic.
Reactions occur in a Mannheim mechanical furnace.
Produces 30-60% HCl
Decomposition of Metal Chlorides by Acids
2. Hargreaves Process & Leblanc Process
2SO2 + O2 + 2H2O + 4NaCl 4HCl + 2Na2SO4
Reaction is at 4000-5500o C Reaction is self-sustaining. Reaction is exothermic. Produces 10-12% HCl
Hydrogen chloride as By-products from
Chemical Processes
1. As a by-product in chlorination of botharomatic and aliphatic hydrocarbons– integration of organic and inorganic chemicals industry
RH + Cl2 RCl + HClRCl + HF RF + HCl
Hydrogen chloride as By-products from Chemical Processes
2. As a by-product of the Leblanc Process
NaCl + H2SO4 NaHSO4 + HCl
NaHSO4 + NaCl Na2SO4 + HCl4HCl + MnO2 2Cl2 + MnCl2 + H2O
Na2SO4 + C + CaCO3 Na2CO3 + CaSO4
Na2CO3 + Ca(OH)2 2NaOH + CaCO3
Hydrogen chloride as By-products from Chemical Processes
3. As a by-product of the Manufacture ofIsocyanate
RNH2 + COCl2 RNCO + 2HCl
But HCl cannot be recycled other than the
regeneration of chlorine!
Group Assignment
1. Enumerate at least five industries which use hydrochloric acid anddescribe how HCl is used or applied in each industry.
2. List down at least seven chemical reactions of HCl with other compounds.Literature source: Kirk-Othmer Encyclopedia.
3. Identify the sources of raw materials for each production methodpresented.
4. Tabulate the operating temperature, operating pressure, enthalpy ofreaction, yield, and other process conditions for the following:
a. Production of HCl via the Saltcake process
b. Productio of HCl via the Hargreaves process
c. Production of HCl as by-product of chlorination of benzene
d. Production of HCl as by-product of the Leblanc process
e. Production of HCl as by-product of the Isocyanate manufacture
INSTRUCTION:S Write your answer on a short bondpaper. Cite references used. Submitassignment on July 13, WED, not later than 5:00 PM. Group members must affix theirsignature.