Ch-3: Seperation techniques Flashcards
What is filtration?
Filtration is a seperation technique used to separate an undissolved solid from a mixture of the solid and a liquid
Describe the process of Filtration
- Filter paper is placed in a filter funnel above another beaker
- The mixture of insoluble solid and liquid is poured into the filter funnel
- Filter paper will only allow small liquid particles to pass through as the filtrate
- Solid particles are too large to pass through the filter paper so it will stay behind as a residue
There is a mixture of solid iodine, sand and salt. Make a plan to seperate all 3 from this solid mixture.
- Heat the solid iodine, it will sublime and get seperated from the mixture
- Add water to the remaining solid mixture. The salt will dissolve but the sand will not.
- Pour the mixture through a filter paper.
- The salt will pass through as filtrate but sand will get stuck on the filter paper as residue.
What is simple distillation?
Used to separate a liquid and soluble solid from a solution depending on boiling point difference
Describe the process of simple distillation
Mixture: salt water / sea water
- The mixture (salt water) is kept in a round bottom flask
- We then heat up the mixture
- On heating, once the mixture reaches 100 degree celcius, water will start to boil
- The water vapour will rise and enter the condenser, turning it into liquid that is collected in the receiver beaker
- After all the water evaporates, all thats left in the round bottom flask is the solid salt
What is fractional distillation?
Fractional distillation is a seperation process used to separate two or more liquids that are miscible with one another depending on their boiling point difference
Function of:
Fractionating coloumn
To seperate the mixture depending on their boiling point difference. lower boiling power distills over first
Function of:
Condenser
To turn gas into liquid and deliver distillate into the receiver beaker
Function of:
Receiver beaker
Must be kept open so that if any gaseous particle present, they can escape. Is used to collect distillate seperately
What is paper chromatography?
Paper chromatography is a seperation technique used to separate substances that have different solubilities in a given solvent
What is the pencil line drawn on the chromatography paper called?
Base line
The line on which a spot of the sample is dropped
How does the solvent travel up the paper?
The solvent travels up the paper by capillary action taking the sample with it
Which substance travels the longest distance?
Higher or Lower solubility?
The substance with the higher solubility travels the longest distance
True/False:
Different spots on the chromatography paper show same components present in the sample
False, Different spots on the chromatography paper show different components present in the sample
True/False:
Base line should not be dipped into the water
True, the chromatography paper should be touching the water but not up to the base line
True/False:
Different substances (sample) travel same distance with same rate
False, Different substances (sample) travel different distance with different rate
What is the Rf value formula?
- Rf =
Distance travelled by sample
—————————————-
Distance travelled by solvent
If one of the chemicals in a paper chromatogram does not show any spot, what would you do to further identify the chemical?
I would spray locating agent, but if its still not visible, i would change the solvent
What is seperating funnel?
Seperating funnel can be used to seperate immiscible liquid mixture depending on their density difference. More dense liquid will be collected first
Ex: the mixture of water and oil can be seperated by seperating funnel
State two physical properties for whih we can do fractional distillation
- boiling point
- miscibility
