Separating mixtures
solid mixtures
Liquid mixtures
filtration
Magnetic attractions
Crystallisation
Filtration helps to separate an insoluble solid from a liquid
It helps to separate the dissolved solid inside a solution.
Examples:
-water and sand
-chalk powder and water
Separates the iron, steel, nickel and cobalt from other metals.
Residue=sand
Filtrate=water
Residue=chalk powder
Filtrate=water
An example would be sugar solution.
At the scrapyard, cranes with electromagnets separate magnetic metals from non-magnetic materials.
sublimation
Used to separate either solid or liquid mixture, that has a solid component which sublimes.
fractional distillation
Simple Distillation
Chromatography
Used to separate two or more soluble substances that dissolve in the same solvent like water or ethanol.
differences between evaporation and crystallisation
Example:
iodine solid and sand
ammonium chloride mixture
Heating followed by sublimation and deposition
Evaporation involves heating the solution to dryness.
On the other hand, crystallisation involves heating the solution until you obtain a saturated solution.
Processes
Used to determine the contents of pen ink to determine if the signature is forged or not.
Process 2: cooling
Process 1: heating
Used to test athletes’ urine samples to find out if they used performance enhancing drugs in their event, if positive, disqualified.
Examples:
liquid air
ethanol and water
crude oil
Examples: separating water from salt(sodium chloride) water.
The processes involved include heating up the solution, and condensing it through the condenser.
It is used to separate a pure solvent from a solution
Used to separate miscible (dissolved) liquid mixtures that have different boiling points
Same as simple distillation but.....
Procedure:
- Draw a line using pencil on the chromatogram paper.
- Put a dye on the line above the solvent
- Close the lid immediately
Longer because the liquid with lower boiling
point boils first and collected, followed by second liquid
Procedure:
- Heating solution
- Liquid with lower boiling point boils first and is later collected after condensation through condenser
- Liquid with higher boiling point will boil later and after condensation, is collected as a liquid in a separate flask
Apparatus (important): a condenser
The condenser is used to cool down the vapour into a pure liquid (distillate).
The Rf value is used to compare the solubility of different substances in the dye
Separating funnel
Another important apparatus is the thermometer.
It is the ratio between the distance traveled by the substance and the distance traveled by the solvent is a constant (c).
This ratio is called the Rf value.
The thermometer is placed usually at the mouth of the condenser. It measures the boiling point of the liquid.
A fractionating column is used in the process.
When both vapours rise up the column, the liquid with a higher boiling point is separated from the liquid with a lower boiling point.
The higher boiling point liquid condenses and falls back into the boiling flask.
If the chromatogram shows only one spot, the substance is pure, therefore, the purity of the substance is 100%
Used to separate immiscible (insoluble in each other) liquids
Water and oil
Procedure:
1.Two liquids allowed to separate from each other (oil floating above water)
- Liquid below is poured and collected, followed by second one