A Polar World?

بسم الله الرحمن الرحيم

Assalamu Alaikum,

Often when hearing the term ‘polar’ the arctic comes to mind. Polar bears, anyone?

***To really get to the point of the post, get past after the two breaks***

But polarity in chemistry refers to a molecule’s electron distribution and intermolecular forces between molecules of the same type. So let’s use water—

Water is H2O. (Really, Faith786?)

The oxygen has a single bond to each hydrogen with a remaining 4 electrons around it. So what happens? One side of water have hydrogens (associated with being a positive (+) charge) and the other side have a load of electrons ( which have a negative (-) charge). The overall molecule is neutral (meaning, there are no added or subtracted electrons–what oxygen and hydrogen originally had are accounted for) but one side is slightly positive and one side is slightly negative.

So if one water molecule met another water molecule, the side that is partially positive (hydrogens) will be attracted to the partially negative side of the *other* water molecule (which is oxygen). So water would line itself up that way and be happy. It is polar.

Now lets look at hexane. Hexane is essentially gasoline (oil) with the formula C6H14. All the carbons are connected in a straight chain and the hydrogens are attached on each side. Carbon makes four bonds so the end carbons on the chain will have three hydrogens attached to them and the middle carbons will have a hydrogen attached to the top and bottom. Like a caterpillar.

Hexane’s electrons are perfectly distributed. The carbons don’t have any electrons left over and all the hydrogen-carbon bonds are being shared and angled from each other nicely. It is nice and neutral and leaves everyone alone. If one hexane molecule sees another hexane molecule, it would simply chill rather than getting attracted on one end. The intermolecular forces are far weaker here and the molecule is considered non polar.

Now if you mixed hexane and water, (which is essentially oil and water), what is going to happen?

2nd grade science teacher demonstration dictates they will not mix. Typically you might hear that one is more dense than the other or one is ‘heavier’ than the other. The reason they don’t mix is because of the difference in polarity.

The water molecule has that partially positive and partially negative sides to it so it wants to line up with another molecule to its partially negative and positive sides respectively. Hexane doesn’t have that so that water molecule will get close to another water molecule. Hexane was denied. =) So all the hexanes will be together because they are don’t bother anyone and the water molecules will be with their crowd because they can get closer with their partial positive and negative sides.

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(For the thermodynamic diehards in the audience)

I have been hearing that some of you believe that the separation of polar and non polar compounds somehow go against the second law of thermodynamics. Second law states that things tend to disorder and the disorder content in the universe is always increasing. So by separating out two different types of molecules (polar vs. non polar), it make more order.

Wrong.

By the two types of molecules separating out, it actually lets them move a lot more freely in their solutions making A LOT of energy and in turn, A LOT of disorder. If a water molecule was in a hexane solution, it would get stuck and it would be hard for it to move around. Not moving=less disorder.

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Moving on, So what is the point?

What would happen if the world didn’t work like that? What if oil could mix in water?

How in the WORLD would you clean that out of the Gulf of Mexico?

This is something to actually think about. If polar and non polar compounds could mix, the world would get really messed up. Your body would become a load of mush because if polar and non polar compounds could mix, it would dissolve your muscles and bones to a slushy puddle with blood, carbohydrates and other weird complicated bio stuff I never understood.

You could not separate out a load of chemicals from plants that are used to make herbal remedies. You would just have to get the good and the bad in your pills.

Plants would have a super hard time separating water from their cells and they wouldn’t be able to release oxygen gas because it is mixed in the sugar they produce. The basic process of photosynthesis:

CO2 + H2O —speed up with sunlight—> sugar (C6H12O6) + O2.

The plant would have a hard time making the reaction go if the H2O is mixed with its cells and O2 would have a hard time being released if it is stuck in a sugar chain/ring.

The melting point and boiling point of everything would pretty much go out of whack–non polar compounds will make polar compounds boil at a lower temperature–>so water would boil at a lower temperature and you would have to cook your eggs longer.

But there would be even heavier implications.

If they could mix, it would mean electrons are more versatile than we think they are. That would me the world would be a lot more reactive than it already is.

Everything would pretty much die. We wouldn’t be able to eat, think, let alone keep our bodies together. The planet would fold on itself because if electrons can move like that, add energy of the earth’s core and electrons would go everywhere and then you’ll have this huge radioactive puddle/cloud in outer space.

(I know there are a lot of assumptions being made, but you get the point)

At times, it seems annoying why it is hard to figure out how things work a certain way but often it is better that it works that way. Maybe it is hard to clean oil off your hands at the sink, but it is better than having the whole universe collapse on itself. Something to think about when studying science–it might be hard, but I am grateful the world is the way it is.

Today’s chemistry blessing: polar and non polar things don’t mix!

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