AS Chemistry unit 1- Halogens

Fluorine at room temperature

Yellow gas

Chlorine at room temperature

Yellow-green gas

Bromine at room temperature

Red-brown liquid

Iodine at room temperature 

Grey-black solid 

Melting point as you descend group 7

increases

Boiling point as you descend group 7

Increases

Atomic radius as you descend group 7

Increases

Electronegativity as you descend group 7

decreases

Chlorine colour in aqueous solution

Colourless

Chlorine colour in an organic solution 

Colourless

Bromine colour in aqueous solution

Orange

Bromine colour in an organic solution

Orange

Iodine colour in an aqueous solution 

Yellow 

Iodine colour in an organic solution

purple

Chlorine and water equation 

Cl₂+H₂O→HCl+HOCl

Cl₂ with cold dilute sodium hydroxide

2NaOH+Cl₂→NaCl+NaClO+H₂O

Cl₂ with hot, concentrated sodium hydroxide

6NaOH+3Cl₂→5NaCl+NaClO₃+3H₂O

Strongest oxidising agent amongst halogens

Fluorine

Strongest reducing agent amongst halides

iodide

Chlorine ions with concentrated sulfuric acid

NaCl+H₂SO₄→NaHSO₄+HCl

Observations from chloride and concentrated sulfuric acid

Misty fumes, heat released, gas produced, solid disappears, pungent smell

Bromide ions with concentrated sulfuric acid 

NaBr+H₂SO₄→NaHSO₄+HBr

Bromide ions in HBr reduce sulfur in H₂SO₄

2HBr+H₂SO₄→Br₂+SO₂+2H₂O

Observations when bromide ions in HBr reduce sulfur in H₂SO₄

Misty fumes, heat released, gas produced, solid disappears, pungent smell, red-brown vapour

Iodide ions with concentrated sulfuric acid

NaI+H₂SO₄→NaHSO₄+HI

Iodide ions in NaI further reduce sulfur in H₂SO₄

2HI+H₂SO₄→I₂+SO₂+2H₂O, 6HI+H₂SO₄→3I₂+S+4H₂O, 8HI+H₂SO₄→4I₂+H₂S+4H₂O

Fluoride ions with concentrated phosphoric acid

KF+H₃PO₄→KH₂PO₄+HF

Chloride ions with concentrated phosphoric acid  

KCl+H₃PO₄→KH₂PO₄+HCl

Bromide ions with concentrated phosphoric acid

KBr+H₃PO₄→KH₂PO₄+HBr

Iodide ions in concentrated phosphoric acid

KI+H₃PO₄→KH₂PO₄+HI

Chlorine and water equation

Cl₂+H₂O→HOCl+HCl

Ozone reaction

3O₂→2O₃