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

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    Hcl Hydrogen Iupac
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Discussion Overview

The discussion revolves around the IUPAC naming of HCl, specifically why it is referred to as hydrogen chloride rather than hydrogen monochloride. Participants explore the implications of naming conventions in chemistry, particularly in relation to the state of the compound (gas vs. solution).

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • Some participants mention that the IUPAC name for HCl is hydrogen chloride, referencing the Red Book for confirmation.
  • One participant expresses uncertainty about the correctness of the name hydrogen chloride and suggests checking color books for exclusions.
  • A participant indicates that the Red Book IR-5.2 may provide an explanation for the naming convention.
  • Another participant notes a distinction between hydrogen chloride as a gas and hydrochloric acid as a solution in water, highlighting that the name can depend on the state of the compound.
  • One participant points out that the naming conventions for covalent bonds involve prefixes, questioning why hydrogen chloride does not use "monochloride." They also mention the electronegativity difference between hydrogen and chlorine.

Areas of Agreement / Disagreement

Participants generally agree that hydrogen chloride is the correct IUPAC name, but there is uncertainty regarding the reasoning behind this naming convention. Multiple viewpoints about the implications of the name and its relation to the state of the compound are present.

Contextual Notes

There are references to specific sections in the Red Book and discussions about naming conventions that may depend on definitions and interpretations of covalent bonding. The discussion does not resolve why hydrogen chloride is preferred over hydrogen monochloride.

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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