Dissolving stuff

[EyeOn]

Compounds don't have electronegativity; atoms have electronegativity.

Oops...forgot that...

The water molecule is polar because of the difference between the electronegativity of the oxygen and that of the hydrogen.

OK...starting to remember...O is more electronegative than H so the dipole pull is in favor of the O.

So the negative end of the molecule is attracted to the positive sodium cations, and the positive side of the molecule is attracted to the chloride anions.

So the water molecule pushes the sodium chloride apart by wedging between the sodium and chlorine atoms in the lattice, because of the dipole H2O has. Am I remotely close??? LOL. Chemistry is not an ace subject for me. Too much confusing math.

BTW...is this dipole H2O has keep the saltwater mixture from turning into acid and base products of NaOH and HCl?

I don't know how else to ask that, but looking at the chemical equation, it makes someone not so fluent in chemistry wonder.."so why doesn't salt water make sodium hydroxide and hydrochloric acid?".

 

[Evilgiraffe]

I may be mistaken, but isn't there a point on that soulbility chart wherein colder water holds more salt than warmer water

Water's weird, it has a maximum density at about 4 degrees C. So, on a volume basis, water at 4 degrees should hold more salt than slightly warmer water.

can ethanol be salted to remove water, as oppossed to distilling?

Distillation of ethanol can only get you to about 95% pure ethanol. At this compostion (a "eutectic mixture") the rate at which ethanol and water boil off become equal and your distillation can no longer separate the two.

To get pure ethanol, you have to remove the last bit of water by adding a chemical drying agent. Bottles of absolute alcohol in the lab will always have small pellets of a "molecular sieve" kicking around in the bottom to mop up any water that gets absorbed from the air.

 

[Evilgiraffe]

ooops, double post

 

[Olowkow]

To get pure ethanol, you have to remove the last bit of water by adding a chemical drying agent. Bottles of absolute alcohol in the lab will always have small pellets of a "molecular sieve" kicking around in the bottom to mop up any water that gets absorbed from the air.

I use lots of the 200 proof lab grade ethanol (100%) that comes in plastic bottles or in glass bottles and I have never seen, or heard of, any "pellets". I'm wondering how they get this pure without them.

Slightly off topic:
Couple of interesting notes about ethanol. It has very low surface tension, compared to water. Try putting some ethanol on teflon pipe wrap tape, it absorbs it like a sponge and turns transluscent, then dries out white again.

Also, to remove hot melt glue from a smooth surface like glass, just a few drops under the glue breaks the seal completely loose. Good tip for temporarily bonding something, and not having to dig the adhesive off. Water won't touch the seal.

 

[Evilgiraffe]

Bog-standard 200 proof alcohol is only guaranteed to be >99.5% ethanol. Plenty of room for some water there.

If the application needs really dry ethanol, like say as a solvent for a Grignard reagent, it needs chemical drying.