Question

How can one dry Hydrogen chloride gas that is highly water soluble?

Answer 1

Hint : The compound hydrogen chloride has the chemical formula $HCl$ and as such is a hydrogen halide. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor.

Complete Step By Step Answer:
Hydrogen chloride is a diatomic molecule, consisting of a hydrogen atom $H$ and a chlorine atom $Cl$ connected by a polar covalent bond. The chlorine atom is much more electronegative than the hydrogen atom, which makes this bond polar.
Upon contact, ${H_2}O$ and $HCl$ combine to form hydronium cations ${H_3}{O^ + }$ and chlorine anions $C{l^ - }$ through a reversible chemical reactions:
${H_2}O + HCl \to {H_3}{O^ + } + C{l^ - }$
The resulting solution is called hydrochloric acid and is a strong acid. The acid dissociation or ionization constant ${K_a}$ is large, which means $HCl$ dissociates or ionizes practically completely in water. Even in the absence of water, hydrogen chloride can still act as an acid.
Hydrogen chloride is produced by combining chlorine and hydrogen, it is an exothermic reaction:
$C{l_2} + {H_2} \to 2HCl$
Small amount of hydrogen chloride can be generated by dehydrating hydrochloric acid with either sulfuric acid or anhydrous calcium chloride, this reaction occurs at room temperature.
$NaCl + {H_2}S{O_4} \to NaHS{O_4} + HCl$
Most hydrogen chloride is used in the production of hydrochloric acid. It is also used in the production of vinyl chloride and many alkyl chlorides. Trichlorosilane is produced using $HCl$ .

Note :
Hydrogen chloride forms corrosive hydrochloric acid on contact with water found in body tissue. Inhalation of the fumes can cause coughing, choking, inflammation of the nose, throat and upper respiratory tract.