Question #e2a78

1 Answer
Jul 19, 2015

Because they are the same chemical compound.


If I understand your question correctly, hydrogen chloride, or #HCl#, and hydrochloric acid, or #HCl#, have the same chemical formula because they are the same compound.

In essence, a hydrogen chloride molecule is formed when a hydrogen atom and a chlorine atom form a covalent bond.

The fact that chlorine is more electronegative than hydrogen ensures that this bond is actually a polar covalent bond, meaning that the bonding electrons spend more time surrounding the chlorine atom than they do the hydrogen atom.

Now, there is a subtle difference between hydrochloric acid and hydrogen chloride

When the molecule is in a gaseous state, it is called hydrogen chloride.

#HCl_((g)) -> color(green)("hydrogen chloride")#

When it is placed in aqueous solution, the compound is called hydrochloric acid.

#HCl_((aq)) -> color(blue)("hydrochloric acid")#

So basically, the #HCl# molecule goes by different names depending on which state it is in

  • in gaseous state #-># hydrogen chloride;
  • In aqueous solution #-># hydrochloric acid.