Acids and Bases

What is the difference between hcl acid and hcl gas?

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December 15, 2008 9:50AM

HCl gas is molecular HCl in the gaseous phase, HCl acid is HCl in solution with water, and can be said to be in the form H+ Cl-. (Or to be a pendant, H3O+ Cl- as techincally protons do not exist on their own in solution.) It is this dissociation of the molecule into constituent ions which gives an acid its properties. On a physical level, HCl gas is a yellow/green gas, and HCl acid is a clear solution.