HCl-hydrogen chloride
HCl or hydrogen chloride is a polar, diatomic molecule. It exists as a gas in its pure form. The electrostatic potential map above shows that HCl has a negative end (red) and a positive end (blue). The space filling model shows that chlorine (green) is very much larger than the hydrogen.
HCl is a major industrial chemical. In 1997, 4,219,000 tons of HCl were produced in the US. These are common ways to prepare hydrogen chloride:
- reacting elemental hydrogen with elemental chlorine
H2 + Cl2 = 2HCl
- treating salt with sulfuric acid
NaCl + H2SO4 = NaHSO4 + HCl
- or as a byproduct of reacting chlorine with hydrocarbons
To a chemistry student, HCl is best known as an aqueous solution, hydrochloric acid. Hydrochloric acid is a strong acid with Kavalue of about 107. That means effectively that 100% of the HCl in water is aquated hydrogen ion and chloride ion.
HCl(aq) = H+1(aq) + Cl-1(aq)
For more background reading on HCl follow these links:
Chemical Backgrounders -Hydrochloric Acid
Sample Materials Safety Data Sheet for Hydrochloric Acid
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