Dissolving Particles

solid particles diffuse through liquid when they dissolve


We have learned during the last few lessons that everything is made of particles and that these particles are always moving. In a solid the particles move the least, however, in a gas the particles move the most.

In the right conditions, when solid particles meet liquid particles they can mix together to form a special mixture called a solution. This process is called dissolving.

This process doesn't happen when any solid or liquid meet (your glass doesn't dissolve when you put water in it) only when the right solid meets the right liquid. When they do dissolve, the solid part is called the solute and the liquid it dissolves in is called the solvent.

Now answer these questions ...

  1. Everything is made of what ?
  2. What are particles always doing ?
  3. What type of particles move the least ?
  4. When solids and liquids dissolve - what is the solid called ?
  5. When solids and liquids dissolve - what is the liquid called ?
  6. What is the mixture called ?
  7. Do all solids and liquids dissolve in each other ?
  8. What solvent do you use to make coffee ?

You scored out of 8 on that test

Dissolving and Diffusing

There is a link between dissolving and diffusing the main difference is that dissolving involves the breaking of bonds like those that hold solid particles together.

Once a solvent and a solute dissolve the particles mix together and then diffuse to form an even mixture of particles.

Dissolving Quickly

When you put some sugar in your coffee you want the solid sugar to dissolve in the liquid coffee to give a sweet solution.

If you want your sugar to dissolve quickly you can do two things. We know that temperature can affect particles - so heating up your coffee will speed up the dissolving process.

The size of the grains of sugar that you use will also affect the speed with which it dissolves. If you put fine, caster sugar in your coffee it will dissolve quickly; big sugar crystals (found in posh coffee shops) will dissolve much more slowly.


... and now these questions

  1. Is sugar a solvent or a solute ?
  2. Is water a solvent or a solute ?
  3. If you want your sugar to dissolve quickly do you use big or small grain sugar ?
  4. Will hot or cold coffee dissolve sugar quickly ?
  5. What things hold solid particles together ?
  6. When things dissolve - what is broken ?
  7. When the coffee and sugar particles mix do they stay in the same place ?
  8. Will the mixing of particles (diffusion) be quicker when the solution is hot or cold ?

You scored out of 8 on that test