Describe a chemical method each for the preparation of sols of sulphur and platinum in water - Chemistry - Surface Chemistry

Question

Describe a chemical method each for the preparation of sols of
sulphur and platinum in water

Tinku Jangra · Accepted Answer

Preparation of Sulphur sol in water:A sulphur sol is prepared by the oxidation of H2S with oxidising agents like HNO3, SO2, Br2 etc
H2S + Br2→S + 2HBrH2S →HNO3H2O + S   ( HNO3 is a strong oxidising agent
 It will only provide  atomic oxygen
)2H2S + SO2→3S + 2H2OPreparation of Platinum sol in water:Platinum sol can be prepared by reducing a very dilute solution of PtCl4 withhydrazine or formaldehyde or SnCl2
PtCl4+2SnCl2→Pt + 2SnCl4PtCl4+2HCHO +2H2O→Pt + 2HCOOH + 4HCl