Metal halides with sulfuric acid
When sodium chloride is reacted with concentrated sulfuric acid, sodium sulfate and hydrogen chloride is formed. This is a displacement reaction.
When sodium iodide is reacted with concentrated sulfuric acid, the iodine ions are stronger reducing agents than bromide ions and reduces sulfuric acid into hydrogen sulfide, and iodide ions are oxidized into iodine. This is a redox reaction.
- NaCl + H2SO4 --> NaSO4 + HCl
- Similar results with other potassium chlorides and fluorides
- 2NaBr + H2SO4 --> NaSO4 + Br2 + SO2 + H2O
When sodium iodide is reacted with concentrated sulfuric acid, the iodine ions are stronger reducing agents than bromide ions and reduces sulfuric acid into hydrogen sulfide, and iodide ions are oxidized into iodine. This is a redox reaction.
- 8NaI + 5H2SO4 --> 4Na2SO4 + 4I2 + H2S + 4H2O
Precipitation reactions
When a solution of lead or silver salts is reacted with a solution containing halide ions, silver and lead halides form as precipitate. The silver or lead chloride, bromide, or iodide can be distinguished by their colors and by solubility in ammonia, so the halide ions can be tested for.
Hydrogen halides
- Hydrogen chloride HCl, hydrogen bromide HBr, and hydrogen iodide HI are strong acids, but hydrogen fluoride HF is a weak acid.
- Thermal stability increases as you go down the group. Hydrogen fluoride HF is the most stable when heated.
http://www.docbrown.info/page07/ASA2group7b.htmhttp://www.nuffieldfoundation.org/practical-chemistry/silver-and-lead-halides
http://www.chemguide.co.uk/inorganic/group7/acidityhx.html
http://www.s-cool.co.uk/a-level/chemistry/group-vii/revise-it/hydrogen-halides
http://www.chemguide.co.uk/inorganic/group7/acidityhx.html
http://www.s-cool.co.uk/a-level/chemistry/group-vii/revise-it/hydrogen-halides