Wednesday, October 27, 2010

Seperating All The Wonderful Glories of Chemistry

Hi this is Hanae here. The smart one, obviously. We'll have to put aside Ancient Greece and such tonight, since the Greeks didn't come up with what I'm going to teach you guys tonight. (although I must admit, I miss imagining I was Greek)

So today we will be learning about the joys of Separation Techniques. There are five main types we will be learning about today:
-Crystallization and Extraction
Scratch that, there are six, I think.

Let's first talk about Hand Separation and Evaporation. A few key points to remember:
-This is when you try and separate solids from solids.
-Magnetic things can be separated using a magnet.
Ex; There are a bunch of coins and you want to separate the pennies from everything else.
- You'd obviously just use your hands and pick the pennies out.
-Evaporation, I'm sure you all know is when you heat up liquids so you get the solid residue/remains.
-Evaporation is used when there is a solid dissolved in liquid solution.
Ex; When you have salt water and you only want the salt.

Second method, (gosh I'm tired already) Filtration
-You can use filtration when there is an undissolved solid inside a liquid.
-You'd use a porous filter to separate the two matters.
-If the pores of the filter are smaller than the particles themselves, obviously the solid stuff will stay on the filter while all the gas and liquid passes through it; solid particles are too rigid to pass through the pores.
-You'd usually use filter paper to do all this.

Third method (trust me, this kills me as much as it kills you), Crystallization
-Use this method when you are separating a solid from a liquid.
-First you'd have to convert the solid into a solute. The solute is usually made via a chemical or physical change.
-After converting the solid into a solute, you'd then separate it using the filtration or floatation method.
-Finally, you evaporate or cool down the substance until the solid comes out as pure crystals. If needed, you can filter the crystals from the remaining solvent.

Fourth Method (I should really get to PHYSICS soon...), Gravity Separation
-This is a pretty straightforward method.
-When you use gravity to separate things based on their density.
-Usually used to separate solids from solids.
-Something called a centrifuge helps do this, and whirls a test tube around at a super high speed making the denser substance sink to the bottom.
-Works most effectively when done with small amounts of material.

Fifth Method! (back to enthusiasm! Yay chem!), Solvent Extraction.
-This is when a component wafts into a solvent when it is shaken with the mixture.
-This works effectively when done with solvents that only dissolve one component.
-When it is a MechanicalMixture, a solid mixed with a solid, you use liquid to dissolve ONE of the solids. The solid is then left behind or dissolved.
-But oh, what if the solvent is insoluble?
-The liquid will then form layers and drain the insoluble solvent.
-This leaves the unwanted substance (solid) behind.

Sixth Method (Not going to lie,I just got distracted by Facebook), Distillation.
-Have you ever seen "distilled water" on your water bottle? Well I'm going to educate you about that.
-You heat the mixture, and substances with a low boiling point vapourizes first.
-Essentially, it is the collecting and condensing of vaporized components.
Seventh and final Method!!...Split into two parts. Chromatography.
-Two types of chromatography:
-Paper Chromatography (PC)
-Thin Layer Chromatography (TLC)
-A mobile phase wooshes the sample over a stationary phase. (graphically speaking)
-Separates complex mixtures like drugs, plastics.
-A highly accurate and precise method.
-Once separated, you can collect the components individually. So basically, it's convenient.
Sheet Chromatography.
-Stationary Phase is a liquid drenched into a sheet of paper.
-Mobile Phase is simply a liquid solvent.
-Some components take longer in the stationary phase.
-Appears in separate spots on the paper after separation is complete. Or after "developing"
-Stationary Phase; a very thin layer of absorbent. It usually coats some sort of sheet.
-Ditto Paper Chromatography, the "developed products" appear on various spots on the sheet after procedure is complete.

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