Group 7 - the halogens -2

HideShow resource information
  • Created by: Shannon
  • Created on: 09-05-14 11:18
View mindmap
  • Group 7
    • Physical properties
      • Flourine
        • Pale yellow gas
      • Chlorine
        • Green gas
      • Bromine
        • Red/brown liquid
      • Iodine
        • Silver solid
      • Appearance in water
        • Flourine
          • N/A
        • Chlorine
          • Virtually colourless
        • Bromine
          • Yellow/orange
        • Iodine
          • Brown
      • Appearance in hydrocarbon solvents: hexane
        • Flourine
          • N/A
        • Chlorine
          • Virtually colourless
        • Bromine
          • Orange/red
        • Iodine
          • Pink/violet
    • Oxidation reactions
      • With non-metals
        • E.g chlorine reacts with sulfur to form sulfur(I) chloride
      • With metals
        • Fluorine & chlorine react with hot iron to form iron(III) halides
        • Bromine is  weaker oxidising agent and so there is a mixture of iron(II) and iron(III) bromide
        • No iron(III) ions form with iodine
    • Reactivity
      • Halogens react by gaining an electron, so they oxidise another species
        • Down the group they become less oxidising
          • Their reducing power increases down the group
    • Disproportionation reactions
      • Halogens react with hot and cold alkali
        • The halogen is simultaneously oxidised and reduced
    • Reactions with conc. sulfuric acid
      • Potassium halides react with conc. sulfuric acid to give acid and a hydrogen halide
        • KF or KCl - HF or HCl gas given off
          • HF and HCl aren't strong enough reducing agents to continue the reaction
        • KBr - HBr gas produced in the first reaction
          • HBr is a strong reducing agent and so reacts with sulfuric acid in a redox reaction
            • SO2 produced
        • KI - HI gas produced in first reaction
          • HI reduces the sulfuric acid the strongest
            • H2S produced
    • Testing for the presence of halides
      • Addition of silver nitrate
        • Flourine
          • No ppt forms
        • Chlorine
          • White ppt
            • Redissolves in dilute NH3
        • Bromine
          • Cream ppt
            • Redissolves in conc NH3
        • Iodine
          • Pale yellow ppt
            • Will not redissolve
    • Reactions of hydrogen halides with water and ammonia
      • Ammonia
        • Produces an ammonium halide
      • Water
        • Produces a strong acid
    • Iodine/Thiosulfate titration
      • Iodine is a  common oxidising agent, whilst thiosulfate is a common reducing agent
      • Starch is used as an indicator
        • Blue/black in the presence of iodine
      • S2O32-
      • Observed colour changes of solution: brown -> pale yellow, pale yellow -> blue/black, blue/black->colourless

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all The Periodic Table resources »