Polar and nonpolar solvents
From this topic, we can get this information that if this subject is a polar solvents, it should be a polar and a solvent.
Therefore, we should know what is a polar first.
1. Polar:

  • The molecule make up by two or more different elements.
  • the molecule should be asymmetrical. (asymmetrical mean the shape which two sides are different.)
Then we should know what is solvent.
2. Solvent: solvent is a liquid that is able to dissolve the solute.
If the molecular is a polar and also is a solvent, it should be a polar solvent. If not, it should be a nonpolar solvent.



There are some examples of polar solvents:

1.water (only dissolve in polar)* H2O1-7732185.jpg

  • Special note: Ionic compound usually dissolve in water not other common polar solvent(For example: NaCl is very difficult to dissolve in methanol,but it can dissolve in water easily).


2. methanol(only dissolve in polar) @methanol.png
3. chloroform (only dissolve in polar)★chloform.jpg
4.ethanol :$ ethanol.png (ethanol can dissolve in polar but it also can dissolve in nonpolar. The hydrogen chain part is a nonpolar group but the OH part is a polar group)

There is a example of the nonpolar solvents:


1. benzene & Benzene_ring-775678.jpg(It is symmetrical, so it is a nonpolar and it is a nonpolar solvent)
(only dissolve in nonpolar)



Dissolving:
there are three attraction which help the solute dissolve in the solvent.
1. The solvent molecule attract the solvent molecules which surround them.
2. The solvent molecule attract the solute particles.
3. The solute particle attract the other solute particles

There are some conclusion of polar, ionic, and nonpolar solutes:


Polar solutes
Ionic solutes
Nonpolar solutes
Polar solvents
Easily to dissolve
Easily to dissolve
Difficult to dissolve
Nonpolar solvents
Difficult to dissolve
Difficult to dissolve
Easily to dissolve

1.Polar and ionic solutes are very difficult to dissolve in the nonpolar solvents.
Why:
The bonds of ionic crystal and polar solutes are very strong. we need enough energy to break those bonds if the nonpolar solvents want dissolve the ionic or solutes. However the nonpolar solvents just have the weak London forces. Nonpolar solvents have not enough energy to break the bonds which hold by the polar or ionic solutes. Therefore polar and ionic solutes are very difficult to dissolve in the nonpolar solvents.

2. Polar and ionic solutes are easily to dissolve in the polar solvents.
Why:
Both of the solutes and the solvents are polar. They have attraction between each other. The polar have dipole-dipole forces and London forces. It has enough energy to break the bond which hold by the original molecular and to form the new molecular.

3. Nonpolar solutes are easily dissolve in the nonpolar solvents.

Why:
Both of the solutes and the solvents are nonpolar. Both of them have not the charge in the end. Therefore they will not attract the polar or ionic solutes or solvents. In addition, both of them just have London forces. Nonpolar solvents have enough energy to break the bonds of the nonpolar solutes. Therefore nonpolar solvents are able to dissolve the nonpolar solutes.

4.Nonpolar are very difficult to dissolve in the polar solvents.
Why:
First of all, the nonpolar moleculars have the London forces. The polar solvents have less London forces than nonpolar. Therefore the polar solvents have not enough energy to break the bonds which hold by the nonpolar. Then the nonpolar are difficult to dissolve in the polar solvents.



In addition:
Many solvents' structure both have the polar group and nonpolar group. If the nonpolar group is larger than the polar group, the nonpolar solutes are more easier dissolve in this solvent. If the polar group is larger than the nonpolar group, the polar and ionic solutes are more easier to dissolve in this solvent.
^ Example:page 207 #22

Reference:
There are some picture are come from the Internet.
*:
http://www.webelements.com/_media/compounds/H/H2O1-7732185.jpg This example is from the textbook.
@: http://upload.wikimedia.org/wikipedia/commons/9/95/Methanol_structure_simple.png This example is frome the textbook.


$ :http://upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Ethanol-structure.svg/529px-Ethanol-structure.svg.png This example is from the textbook.
& :
http://www.62stockton.com/spacebirds/uploaded_images/Benzene_ring-775678.jpg This example is from the textbook.
^ :This example is from the textbook.

★: http://www.asmalldoseof.org/historyoftox/1800s/chloform.jpg