Chemistry Blog Entry 6

SEPARATION TECHNIQUES


There were mainly 3 techniques we actually learnt about.

1. Crystallization ( most interesting!!!)
2. Simple Distillation
3. Chromatography ( 2nd interesting) 

There are actually many separation methods but those above were mainly the ones that were highly emphasized on.

CRYSTALLIZATION

To separate a dissolved solute from a solution 

Commonly used to separate the heat labile solutes from their solutions

Keywords: ** Heat-labile : substances which are easily decomposed

Experiment : Forming crystals 

We used copper sulfate which is actually a blue powdery substance to create crystals. 

My partner and I did the experiment that did not involve rapid cooling. Thus, we did not really put it into the beaker filled with ice. 

The scariest part of the experiment was the part which you had to check for the formation of crystals using the glass tube. I was really afraid to mix the bottom part ( in case somehow we actually get burnt) so we ended up saturating the mixture a LITTLE bit. Hence we had to add more water , boil it again and get the crystals. 

Before all of this, we had to use a method called FILTRATION. Basically, we had to filter all the copper sulfate chunks so that there will be no impurities. 

Filtration -> Separation of insoluble substances from liquid 

Insoluble substance- Residue

Usage of filter paper

Keywords:** Saturated solution: A solution that contains the maximum amount of solute dissolved in a given volume of a solvent at a particular temperature

DIFFERENCES BETWEEN RAPID COOLING AND SLOW EVAPORATION 

Rapid cooling of saturated solution - small and ill-shaped crystals

Slow evaporation of a cold saturated solution - Large and well defined crystals obtained

SIMPLE DISTILLATION 

Purpose: To separate the solvent from a solution of solute

Purifies liquid 

- Always use a round bottom flask 

Purpose of boiling stones: To allow the surface of the liquid to be in equilibrium with a gas 

It prevents water from being heated beyond its boiling point.

Purpose of Condenser: To cool the water vapor and condense it to form water droplets

FINAL PRODUCT: DISTILLATE

( Shown to use with the coke) 

Leftover product: Water and sugar in separate apparatus

CHROMATOGRAPHY 

To separate a mixture of solutes with different solubility and degree of absorption 

Chromatography paper 

RETENTION FACTOR: 

Rf value = Distance moved by substance 

              Distance moved by solvent 

Uses: 

Separate and identify compounds 

** A compound is a two or more elements chemically combined. 

** Locating agent: Chemical substance that will produce colored products on reaction with the colorless compounds 

**** Solvent front 

DECANTING 

Separating insoluble solids from liquids 

That's all!

Thank you!