IGCSE›Oxford AQA IGCSE Chemistry›Mind mapsSimple Diffusion ExperimentsOxford AQA IGCSE Chemistry: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsWhat is it?Spreading from high to low concentrationContinues until particles are evenly spreadCaused by random particle motionWhat it showsDirect evidence that particles existParticles move constantlySpreading without stirring: random, independent motionBromine in airOrange-brown bromine vapour in a gas jarColour spreads into the air-filled jarShows diffusion in gasesDiffusionevidence for particlesBrX2\ce{Br2}BrX2NHX3\ce{NH3}NHX3HClAmmonia and HClCotton wool with ammonia and HCl at tube endsGases meet and form white ammonium chloride ringRing forms nearer the HCl endAmmonia is lighter, so diffuses fasterLiquidsPotassium manganate(VII) crystal in waterPurple colour spreads without stirringLiquid particles are closer and slowerExam tipsDiffusion is faster in gases than liquidsExplain ring position using particle mass and speedLighter particles diffuse faster