Separation Of Mixtures Flashcards
What is a compound?
Pure substances that contains 2 or more elements chemically combined. At least 2 types of atoms bonded together.
What is an element?
Pure substance that cannot be split up into 2 or more simpler substances by chemical processes or electricity.
What is a mixture?
2 or more different types of substances which are not chemically combined together.
What are some examples of mixtures?
- Sea water
- Chlorine solution
- Bronze alloy
- Steel alloy
- Natural air.
What is the purpose of simple distillation?
- Used to separate a solid DISSOLVED in a liquid.
2. Only liquid obtained.
What is the substance with the lower BP obtained by simple distillation called?
Distillate.
What is the function of the Liebig condenser?
- Condense vapor given off (Substance with lower BP) back into liquid form.
- Kept at room temp by running tap water through it.
What is the function of the thermometer in simple distillation?
To monitor at the temp of vapor entering condenser is not higher than the BP of distillate.
What is the purpose of evaporation to dryness/ crystallization?
- Used to separate a solid dissolved in a liquid.
2. Only solid is obtained.
What is the difference between the products obtained by crystallization and simple distillation?
- SD obtain substance with lower BP.
2. C obtain substance with higher BP.
Why is crystallization not suitable for certain salts?
They are easily decomposed.
What is the purpose of filtration/decanting?
- Uses to separate a solid suspended in a liquid.
2. Eg flour and water
How can we further purify the residue after filtration?
- Washing residue by rinsing with distiller water.
2. Drying residue between sheets of filter paper.
What is the purpose of fractional distillation?
- Used to separate 2 miscible liquids.
2. Eg water and alcohol
Which substance will be the distillate for simple or fractional distillation?
Substance with lower BP.
- temp of thermometer should be at BP of distillate.
What is the function of the fractionating column?
Example:
- When heating ethanol solution at 78, ethanol evaporate.
- Some water also evaporate, along ethanol.
- Fractional column provides large surface area for water vapor to condense.
What is the similarity between the types of mixtures separated by simple and fractional distillation?
Both separate mixtures by their BP.
When would simple or fractional distillation be used?
- SD separates mixtures with large differences in BP( eg sodium chloride1400 and water100)
- FD separates mixtures with small differences in BP.
What are some applications of fractional distillation?
- Liquid air
2. Crude oil(petroleum)
What is the purpose of a separating funnel?
Used to separate 2 immiscible liquids.
What are the properties that we have to look for when separating solids?
- Attracted to magnet
- Able to sublime when heated.
- Soluble in water or other solvent?
When is solution filtration used?
When one solid is soluble in water, while the other one is not.
Eg. Mixture of salt and sand.
When is sublimation used?
When one solid is able the sublime, while the other may not.
Eg mixture of iodine and sand.
What are some substances that sublimes?
- Ammonium chloride
- Iodide.
- Aluminum chloride
- Naphthalene
- Carbon dioxide.
When is separation by magnetism used?
When one solid is attracted by magnet, while the other solid is not.
Eg iron fillings and sand.
Why do we separate mixtures?
- Purification
- obtain clean sample of each component - Identification
- Analyze components of that mixture.
What is used to identity components of a mixture?
Paper chromatography
What are some things we need to take note of during paper chromatography?
- Ensure pencil line is kept above solvent level.
- Solvent must be able to dissolve all components of sample mixture.
- ‘Start line’ drawn in pencil or ink will dissolve into solvent.
