The reactions of sodium halides with concentrated sulfuric acid

The reactions of sodium halides with concentrated sulfuric acid

1. Sodium chloride

   • steamy fumes of hydrogen chloride are seen
   • solid sodium hydrogensulfate is evolved
   • NaCl (s) + H2SO4 (l) --> NaHSO4 (s) + HCl (g)
   • NOT a redox reaction as the oxidation state has not changed as the chlorine ion is too weak a reducing agent
   • acid-base reaction

2. Sodium fluoride

   • steamy fumes of hydrogen fluoride are seen
   • fluoride ion is an even weaker reducing agent than the chloride ion.

3. Sodium bromide

   • steamy fumes of hydrogen bromide are seen
   • brown fumes of bromine are seen
   • colourless sulfur dioxide is also formed
     • because the bromide ions are strong enough reducing agents to reduce the sulfuric acid to sulfur dioxide

4. Sodium iodide

   • steamy fumes of hydrogen iodide are seen
   • black solid of iodine forms
   • bad egg smell of hydrogen sulfide gas
   • yellow solid sulfur may occur
   • colourless sulfur dioxide is also evolved