Hydrochloric Acid is written HCl. With school atomic masses the molar mass is 36.5 g/mol. Hydrogen chloride forms hydrochloric acid when dissolved in water, where it behaves as a strong acid.
H₂O
WaterNH₃
AmmoniaCO₂
Carbon DioxideH₂O₂
Hydrogen PeroxideSO₂
Sulfur DioxideNO₂
Nitrogen DioxideHCl
Hydrochloric AcidH₂SO₄
Sulfuric AcidHNO₃
Nitric AcidCH₄
MethaneC₂H₆
EthaneC₃H₈
PropaneC₄H₁₀
ButaneC₂H₄
EthyleneC₂H₂
AcetyleneC₆H₆
BenzeneC₇H₈
TolueneC₁₀H₈
NaphthaleneC₆H₁₂
CyclohexaneCH₃OH
MethanolC₂H₅OH
EthanolCH₃COOH
Acetic AcidHCHO
FormaldehydeCH₃COCH₃
AcetoneC₄H₁₀O
Diethyl EtherC₂H₇N
EthylamineC₂H₅NO
AcetamideC₆H₁₂O₆
GlucoseC₆H₁₂O₆
FructoseC₁₂H₂₂O₁₁
SucroseCO(NH₂)₂
UreaC₂₇H₄₆O
CholesterolC₉H₈O₄
AspirinC₈H₉NO₂
AcetaminophenC₁₃H₁₈O₂
IbuprofenC₈H₁₀N₄O₂
CaffeineC₆H₆N₂O
NicotinamideC₆H₈O₆
Ascorbic AcidC₁₆H₁₈N₂O₄S
Penicillin GC₂H₆O₂
Ethylene GlycolC₈H₈
StyreneC₂H₃Cl
Vinyl ChlorideC₃H₅NO
AcrylamideC₆H₁₁NO
CaprolactamLiCl
Lithium chlorideNa₂O
Sodium oxideNaCl
Sodium chlorideMgF₂
Magnesium fluorideAlCl₃
Aluminum chlorideCaO
Calcium oxideCaC₂
Calcium carbideKNO₃
Potassium nitrateMg₃(PO₄)₂
Magnesium phosphateAl₂(SO₄)₃
Aluminum sulfateMg(OH)₂
Magnesium hydroxideNH₄Cl
Ammonium chlorideNH₄OH
Ammonium hydroxideCuO
Copper(II) oxideCu₂O
Copper(I) oxideFeSO₄
Iron(II) sulfateFe₂(SO₄)₃
Iron(III) sulfatePbCO₃
Lead(II) carbonateMgO
Magnesium oxideAl₂S₃
Aluminum sulfideLiF
Lithium fluoride(NH₄)₂S
Ammonium sulfideKF
Potassium fluorideNiCl₂
Nickel(II) chlorideKCN
Potassium cyanideCH₃COONa
Sodium acetateCaCO₃
Calcium carbonateNa₃P
Sodium phosphideBeBr₂
Beryllium bromideFeO
Iron(II) oxideHg₂Cl₂
Mercury(I) chlorideHg(NO₃)₂
Mercury(II) nitrateCH₃COOCu
Copper(I) acetateSiO₂
Silicon dioxideP₄O₁₀
Tetraphosphorus decaoxideN₂O₅
Dinitrogen pentoxideCO
Carbon monoxideHF
Hydrogen fluoridePCl₅
Phosphorus pentachlorideCF₄
Carbon tetrafluorideSF₆
Sulfur hexafluorideNBr₃
Nitrogen tribromideN₂O
Dinitrogen monoxideN₂O₃
Dinitrogen trioxideCS₂
Carbon disulfideCl₂O₇
Dichlorine heptoxideBF₃
Boron trifluorideCCl₄
Carbon tetrachlorideSO₃
Sulfur trioxideSiCl₄
Silicon tetrachlorideP₂S₅
Diphosphorus pentasulfideBCl₃
Boron trichloridePBr₃
Phosphorus tribromideCBr₄
Carbon tetrabromideNF₃
Nitrogen trifluorideOF₂
Oxygen difluorideNCl₃
Nitrogen trichlorideH₂S
Hydrogen sulfidePH₃
PhosphineBeCl₂
Beryllium chlorideHCN
Hydrogen cyanideClF₃
Chlorine trifluorideXeF₂
Xenon difluorideTetrahedral
Diatomic linear
Hydrogen chloride forms hydrochloric acid when dissolved in water, where it behaves as a strong acid. It is important in industrial chemistry and biological digestion.
Properties
Molar mass
36.461 g/mol
Boiling point (liquid HCl)
−85 °C
Bond length
127.4 pm
Dipole moment
1.08 D
pKa
−6.3 (strong acid)
Uses
Steel pickling and cleaning · pH control in industry · Production of chlorides and PVC intermediates
Exam note
Systematic name
Hydrogen chloride
Compound class
It is a polar covalent molecule. Its aqueous solution is hydrochloric acid, a strong acid.
Formula unit
One hydrogen atom and one chlorine atom share a covalent bond.
Aqueous solution
It ionizes completely in water: HCl → H⁺ + Cl⁻. That solution is the main acid in the stomach.
Watch the formula
With school atomic masses the molar mass is 36.5 g/mol. Chlorine is taken as 35.5, not 35 or 36. Do not mix hydrogen chloride gas with the aqueous acid. In pH calculations it is treated as fully ionized.
Molar mass calculation
Masses given in the question come first. When none are given, school values put the total at 36.5 g/mol.
+
= 36.5 g/mol
HCl
The same count with periodic-table atomic masses gives 36.458 g/mol.
| Element | Atom count | Contribution (g/mol) | Mass % |
|---|---|---|---|
| Chlorine (Cl) | 1 | 35.450 | 97.2 |
| Hydrogen (H) | 1 | 1.008 | 2.8 |
| Total | 36.458 | 100 |
Common questions
What is hydrochloric Acid?
Hydrogen chloride forms hydrochloric acid when dissolved in water, where it behaves as a strong acid. It is important in industrial chemistry and biological digestion.
What is the formula of hydrochloric Acid?
Hydrochloric Acid is written HCl. The systematic name is Hydrogen chloride. One hydrogen atom and one chlorine atom share a covalent bond.
What is the molar mass of hydrochloric Acid?
Hydrochloric Acid has a molar mass of 36.458 g/mol from the atomic masses on the periodic table. With school atomic masses the total is 36.5 g/mol, counting 1 chlorine and 1 hydrogen.
How does hydrochloric Acid behave in water?
It ionizes completely in water: HCl → H⁺ + Cl⁻. That solution is the main acid in the stomach.
What is hydrochloric Acid used for?
Hydrochloric Acid is used for steel pickling and cleaning, pH control in industry and production of chlorides and PVC intermediates.
What should you watch for with hydrochloric Acid on an exam?
With school atomic masses the molar mass is 36.5 g/mol. Chlorine is taken as 35.5, not 35 or 36. Do not mix hydrogen chloride gas with the aqueous acid. In pH calculations it is treated as fully ionized.