Question

Differentiate between a saturated and unsaturated solution. how will you test whether a given solution is saturated or not ?

Answer 1

Saturated means that the solute contains as much substance as can possibly dissolve in it. It will be at equilibrium, since the material going to solid and going to solution will equal. Basically it means that no matter how hard you try, you will not dissolve any more solid in your liquid. For example, take sugar and water. You can add sugar and add sugar and add sugar and stir, but at some point no more sugar will dissolve. It stays as a solid at the bottom of the glass. That's a saturated solution. 

Unsaturated means it's not yet to the saturation point. More solid can dissolve in the solution. 

Now for supersaturated, say you throw your water and sugar mixture in the microwave and heat it up. You're shifting the equilibrium point to the right, and so more of the solid sugar will dissolve. In fact, you can probably melt it all! Now if you cool it and you are careful not to bump the container, ll the sugar that dissolved into solution will stay in solution. This is called supersaturation. Basically it wouldn't have happened naturally, but because you changed the temperature more was able to melt. The cool thing about supersaturation is that if you add a "seed", or drop in some extra sugar or otherwise cause a disturbance, you can precipitate the extra sugar out of the solution and go back to a state of saturation. 

Answer 2

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By adding  cold dilute Baeyer's reagnant

More about Baeyer's Reagnant.

• Baeyer's reagnant is cold dilute

• It is an oxidising agent.

If this mixture is added to an unsaturated compounds such as alkenes or alkanes then :

• Purple colour of  the reagnant changes .

• It is first converted to a green compound   which is unstable in alkaline medium.

• This again changes to brown  

• The supernatant liquid gets decolourised.

However saturated compounds do not respond to the above test.

In simple words........... your answer is :

In order to test unsaturation first add cold dilute Baeyer's reagnant.

If the reagnant decolorises from purple to colourless then the compound is unsaturated

Otherwise if the reaction does not occur , then it is a saturated compound.

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