2.  A bottle of perfume is opened in the room why can we smell it after a while  This is called diffusion  Diffusion is when particles move from a high concentration to a low concentration

3.  Concentration means how many particles there are  High concentration = lots of particles  Low concentration = less particles HIGH concentration of red particles LOW concentration of red particles The RED particles SPREAD out until they are the same on both sides

6.  We can look at the diffusion of bromine gas from one jar to the other

7.  In this experiment two gases diffuse towards each other  Which particles move faster? Ammonia or acid?  The ammonia particles are lighter than the hydrochloric acid particles, so they diffuse faster cotton wool soaked in ammonia solution cotton wool soaked in hydrochloric acid White ring forms closer to acid The white ring is made of ammonium chloride

8.  Diffusion happens quickly in gases, why?  In gases there are lots of spaces between the gas particles  The added particles can diffuse (spread out) quickly  Gas particles are moving very fast and so the added particles spread out faster

9.  Diffusion can also happen in liquids  This is because the particles in liquids can move around  Diffusion in liquids is slower than diffusion in gases because the particles in a liquid move more slowly  Also there are less spaces between the liquid particles

10.  Diffusion does not happen at all in solids, why?  The particles in a solid can only vibrate on the spot and cannot move around  In order for diffusion to occur the particles must be able to move around

11.  When we add a purple crystal of potassium permanganate to water  We observe diffusion of the purple colour

12.  When we add blue copper sulphate crystals to water, we observe diffusion

13.  We know that matter (solids, liquids and gases) are made up of small particles  If we take a coloured solution and dilute it several times the colour fades away but it does not disappear  This indicates there are lots of small particles in the coloured solution