Why is HCl called Hydrogen Chloride (by IUPAC naming)?

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SUMMARY

The IUPAC name for HCl is Hydrogen Chloride, which refers specifically to the gaseous form of the compound. According to the Red Book IR-5.2, this nomenclature is correct and distinguishes between the gas and its aqueous solution, known as Hydrochloric Acid. The naming convention reflects the nature of the compound, as it is classified based on its state rather than its molecular composition. Additionally, the bond between hydrogen and chlorine is polar covalent, with an electronegativity difference of 0.96, which is below the threshold for ionic bonding.

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pkc111
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Homework Statement
Why is HCl called Hydrogen Chloride (by IUPAC naming) and not Hydrogen Monochloride? It has a polar covalent bond (not ionic).
Relevant Equations
Covalent bonds have a prefix on the last name according to IUPAC.
The difference in electronegativity between H and Cl is about 0.96, well and truly below the 1.7 generally regarded as the ionic/covalent border.
Hydrogen Monochloride
 
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I would check one of the color books (never remember which one is which) to see if:
1. hydrogen chloride is really a correct IUPAC name
2. it is not one of the exclusions
 
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Red book says the IUPAC name is hydrogen chloride. I am not sure why though.
 
I feel like Red Book IR-5.2 explains it.
 
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Is this the bit that explains it..? (from IR 5.2)

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That's my understanding.
 
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Ok thanks Borek, very helpful!
 
Last edited:
Gee! All this time I thought it was called hydrochloric acid.
says it is just the gas that is called hydrochloride. So I also learned a second new-to-me chemistry concept:
a compound can have a different name depending on its state: gas or liquid.
 
Liquid hydrogen chloride is still hydrogen chloride. Hydrochloric acid is a solution of HCl in water.
 
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pkc111 said:
Homework Statement:: Why is HCl called Hydrogen Chloride (by IUPAC naming) and not Hydrogen Monochloride? It has a polar covalent bond (not ionic).
Relevant Equations:: Covalent bonds have a prefix on the last name according to IUPAC.
The difference in electronegativity between H and Cl is about 0.96, well and truly below the 1.7 generally regarded as the ionic/covalent border.

Hydrogen Monochloride
The naming and abbreviating work the other way around. The compound is Hydrogen Chloride (for the gas) and Hydrochloric Acid (for the solution in water). The written symbolization for Hydrogen is H. The written symbolization for Chlorine is Cl.
 

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