I have thought the HCl is an ionic compound since it disassociates in water. However I read in my chemistry book that HCl is molecular. So what is it? Are all acids molecular or just the ones like HF, HCl, HBr, etc?
HCl is a stable molecule that can exist in the gas phase. As an isolated molecule, it has a permanent dipole moment, so the sharing of electrons in this molecule is not equal -- chemists would say that it shows partial ionic character. Interestingly, as you increase the bond distance of the molecule in the gas phase, it will dissociate into neutral hydrogen and neutral chlorine atoms (lowest energy path) -- i.e. the percent ionic character will decrease with increasing bond length. You can see the same behavior in a gas-phase NaCl molecule, as well. The diatomic molecule shows partial ionic character, but will dissociate to neutral atoms. You can read about some interesting chemical physics about the reverse process if you look up "harpoon mechanism".barryj said:I have thought the HCl is an ionic compound since it disassociates in water. However I read in my chemistry book that HCl is molecular. So what is it? Are all acids molecular or just the ones like HF, HCl, HBr, etc?
The chemical formula for HCl is written as HCl because it is composed of one hydrogen atom and one chlorine atom.
HCl is a molecular compound because it is composed of covalently bonded atoms, rather than ions.
HCl is formed through the chemical reaction of hydrogen gas (H2) and chlorine gas (Cl2).
Ionic compounds are formed through the transfer of electrons, resulting in ions with opposite charges that are held together by electrostatic forces. Molecular compounds, on the other hand, are formed through the sharing of electrons between atoms in a covalent bond.
HCl is a strong acid because it dissociates completely in water, producing a high concentration of hydrogen ions (H+) in solution.