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Seperating mixtures (Temperance) - Coggle Diagram
Seperating mixtures (Temperance)
Why?
To obtain useful substances
Eg: O2+N
To study properties
To avoid consequences
Purification techniques
Sublimation/magnetic attraction
Solid-Solid
Used for when solid substances cn sublime when heating
Eg of sublimed substances: Dry ice, iodine crystals, napthelene
In printing process using heat transfer
Dye onto paper or fabric
Filtiration/Evaporation
Solid-liquid
Crystallisation/Chromatography
To separate soluble solid from its non-heat-stable solution
Steps to obtain solublr salt
1.Salt solution is filtered to remove solid impurities
2.Filtrate heated to remove most of solvent to become saturated
(enables crystals to easily form)
3.Saturated solution is left to cool to allow large-size crystals to form
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Crystallistaion in daily life
Important in food tech
Used in production in silicon which is main part of devices
Chromatography
To separate dissolved small amount of substances
Different parts in mixture have different solubility in solvent
Process
1.Small amount of concentrated sample is placed on chromatographic paper
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Usefulness
Identify contents of mixture
Test purity of a substance
Advantages
Only small sample is needed
Fast and accurate analysis
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Food/dyes/poison
Simple distillation
Condenser
Ensures coldest part of condenser is present before vapour escapes
Boiling stones
Smoothen boiling by reeducing bumpoing of liquid
Thermometer
Placed near opening of condenser to measure vapour temperature
Conical flask
Used as receiving flask
Application
Obtaining desalinated water
Imporves quality of drinking water
Used to extract the natural oils from flowers/herbs
When substance is dsitilled, temperature remains constant at boiling point
Liquid collected is distillate
Gentle blue flame is used for heating
If distillate is volatile, receiving flask is filled with ice water
Evaporation used if dissolved solid is heat-stable
Process
1.The solution in the dish is heated until solvent fully dried
Dried salt crystals are obtained in the dish
Application in daily life
Evaporation of seawater gives us common salt
Evaportaion of sweat to keep us cool
Liquid-liquid
Fractional distillation
Liquid with lower boiling point: distilled first
Fractioning column allows liquid with higher boiling point to condense and fall back
Application
Used in oil refineries to separate petroleum
Used to separate ethanol products
Separates liquified noble gases
Filtiration
Features: Residue, filter funnel, filter paper, filtrate, pores
Small liquid particles passs through pores
Large solid particles trapped on filter paper
Residue=insoluble solid on filter paper
Liquid passing through pores=Filtrate
Filter paper has tiny pores so an insoluble solid larger than pore cannot pass through
Eg of mixture
Sand and water
Brewed coffee containing ground coffee
Insoluble silver chloride in sodium nitrate solution
Residsue=silver chloride
Filtrate=sodium nitrate solution
Residue=ground coffee
Filtrate=brewed coffee
residue=sand
Filtrate=water
Application of filtration
Sink filter removes large food particles from entering drainage system
Tea bag prevents tea grains from spreading in water
Sieve separates brewed coffee from ground coffee
Filtration is used to remove suspended soils from greases in used water
Filtration removes unwanted impurities from rainwater
Filtration in human body
The kidneys of mammals clean the blood to take out bad stuff.
The nostril hair filters and removes dust and large suspended particles from the inhaled air.
Singapore uses reverse osmosis to obtain desalinator water
It is a filtration method which uses a special type of membrane
Removes large unwanted particles from seawater
Eg:salts
Precautions for chromatography (must memorise
Draw starting line with pencil not pen
Pencil is an element will not be separated by solvent
Use callipary tubes to place concentrated sample on paper
Prevents overlapping of components
Solvent should be below starting line
Prevents sample from dissolving into solvent
Solvent should be high as possiblre
Ensures components are fully separated
Jar should be covered with lid when using volatile solvent is used
Prevents solvent from evaporating too fast
Ensures jar is saturated with solvebt vapour
How to analyse chromatogram
1 spot, X is pure substance, only 1 component
Different distance travelled, M and N have different solubility in solvent
M is more soluble, travels faster and farther
3 spots, X is mixture, 3 components
Complete matching spots, X and Y are indentical
Smudge, too much X placed on starting line
Partial matching spots, X and Y have 2 identical components
X still on staring line, X does not disolve in solvent
Sample made up of other samples
X has 2 components of Y and 1 Z
