Haniff Simple distillation and fractional distillation Introduction If I have a solution of copper sulphate how might we obtain the solvent Would evaporation be a suitable technique Introduction ID: 536868
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Slide1
Ena Haniff
Simple distillation and fractional distillationSlide2
Introduction
If I have a solution of copper
sulphate
, how might we obtain the solvent?
Would evaporation be a suitable technique?Slide3
Introduction
In this lab session we are going to use a separation technique that retrieves the solvent from a solution
We are also going to separate two MISCIBLE liquidsSlide4
Simple distillation
The apparatus is set up as shown belowSlide5
The process
The solution is heated
What happens at this point?
The vapour rises up the flask and enters the condenser
What do you think will happen to the remaining solution in the flask?
It will become more concentratedSlide6
The process
The
vapour
in the condenser is cooled by the flow of cold water in the outer jacketWhat effect does this have on the vapour?
It causes the
vapour
to condense
What is the liquid that is collected in the receiving flask?
The distillate, pure waterSlide7
Aim: To separate a solution and obtain the solvent
Apparatus and materials:
Thermometer,
condenser, distillation flask,
bunsen
burner,
copper
sulphate
solution,
retort stand,
receiving flaskSlide8
DiagramSlide9
Method
The apparatus was set up as shown in the diagram
Observations were noted
Observations
The solution started to boil at …..°C.
Colourless
vapour
evaporated and formed drops of clear liquid in the condenser.
The drops ran down the condenser and were collected in the receiving flask.
The solution in the flask became darker blue in
colour
The solid eventually remained in the round bottom flask.Slide10
Simple distillation: Discussion
Simple distillation is used to separate and retain the solvent from a solution
eg
. To obtain water from sea water.The method is based on the principle that the solvent is more volatile than the solute and evaporates (volatile measures the tendency to vaporise)The solid remains in the flask and is called the residueThe distilled product is called the distillateSlide11
Simple distillation: Discussion
During the process as heat is applied, the water began to boil off and became water
vapour
which rose up to the top of the flaskThe water vapour entered the condenser where cold water from the inlet caused the water to condense and run off into the receiving flaskAs the water is removed from the solution, the solution got deeper in colour because it became more concentrated.Slide12
Simple distillation: Conclusion
The separation technique of simple distillation was effective in retrieving the solvent from a solution
The distillate obtained is water
Solution pure solvent (as vapour) pure solvent (as liquid)Slide13
Aim: To separate a mixture of miscible liquids
Apparatus and materials:
Fractionating column
Thermometer, condenser,
3 distillation flasks,
bunsen
burner,
Solution (alcohol and water),
retort stand, Slide14
DiagramSlide15
Method
The apparatus was set up as shown in the diagram
Observations were noted
Observations
The solution started to boil at …..°C.
Vapours
evaporated from the solution and travelled up the fractionating column
The
vapours
cooled and condensed in the column
Clear,
colourless
drops condensed and ran down the condenser into the receiving flask where they were collected
After the first fraction was obtained, a sharp rise in temperature was noted and a second fraction was collected then
The temperature then remained at 100°C and a third fraction was collected containing a
colourless
liquid.Slide16
Fractional distillation: Discussion
Fractional distillation is used to separate two miscible liquids (liquids that are readily dissolved in one another)
This technique is based on the principle that one of the liquids is more volatile than the other (has a lower boiling point and
vaporises first)The boiling point of ethanol is 78° and pure water is 100°Slide17
Fractional distillation: Discussion
As the mixture of liquids was heated, the
vapours
rose up the fractionating column and continually condensed and vaporised, with the lower boiling point liquid (the more volatile one), rising to the higher part of the columnThis liquid condensed first and was collected as the first fraction
The thermometer measures the temperature of the
vapour
at the top of the column and
indicated
what liquid is driven offSlide18
Fractional distillation: Discussion
When
the temperature reaches the boiling point of the second liquid, that is then distilled into another container.
Fractional distillation is used on an industrial scale in the separation of liquid air and the refining of crude oil.Slide19
Conclusion
A mixture of miscible liquids was separated by the method of fractional distillation
The first fraction collected was alcohol and the third fraction was water
The second fraction collected a mixture of two fractions.Slide20
Applications of fractional distillation
Can you suggest an application of fractional distillation?
Separation of crude oil