Alcohols Flashcards
(15 cards)
Give two reasons why the apparatus shown in the above figure is not safe. 2 marks
flask not clamped
allow only the condenser is clamped
sealed system / bung in condenser
allow explanation of effect of bung being there e.g.
pressure build up
not reference to incorrect water direction
State two more mistakes in the way the apparatus is set up in above figure ( oxidation of primary alcohols)
- Direction of water flow through the condenser
- Thermometer is not needed for the refulx method
State a simple chemical test that distinguishes the propanoic acid from the
propan-1-ol.
Give one observation for the test with each substance
Add sodium carbonate
Propanoic acid= we can see bubbles/ effervescene
Propan-1-ol- no visible change
Which compound is produced when 1-phenylethanol reacts with acidified
potassium dichromate(VI)?
A C6H5CH2CH2OH
B C6H5CH2CHO
C C6H5COCH3
D C6H5CH(OH)CH3
C- 1-phenylethanol is a secondary alcohol, oxidises to a ketone
Which statement is correct about the production and use of ethanol as a biofuel?
A Biofuel ethanol is produced by the fermentation
of glucose in the presence of yeast and air.
B Biofuel ethanol is purified by fractional
distillation.
C No carbon dioxide is released when biofuel
ethanol is burned.
D Biofuel ethanol burns with a cleaner flame than
ethanol made by hydration of ethene.
B
Which compound can be oxidised to form (CH3)2CHCOCH3?
A 2-methylpropan-1-ol
B 2,2-dimethylpropanol
C 2-methylbutan-2-ol
D 3-methylbutan-2-ol
D- secondary alcohols oxidise to form ketones
In the UK industrial ethanol is now produced by the direct hydration of ethene.
This process has largely replaced the fermentation method.
Which is a likely reason for this change of method?
A The direct hydration route produces purer ethanol.
B The direct hydration route employs milder conditions.
C The direct hydration route does NOT use a catalyst.
D The direct hydration route produces ethanol by a
slower reaction.
A
Describe a test-tube reaction, on the product, to show that the cyclohexanol had been dehydrated.
State what you would observe
2 marks
Add bromine water
Colour change observed from orange to colourless
Suggest why sodium carbonate solution was used to wash the distillate. 1 mark
Na2CO3 would neutralise the H3PO4
Explain why it is important to open the tap of the separating funnel periodically. ( During separation of products of distillation) 1 mark
Prevent build up of gas which would lead to an inc in pressure
Give a property of anhydrous calcium chloride, other than its ability to absorb water, that makes it suitable as a drying agent in this preparation. 1 marks
Does not dissolve in/react with the cyclohexene
Describe the apparatus used to remove the drying agent by filtration under reduced pressure. Your description of the apparatus can be either a
labelled diagram or a description in words.
Buchner funnel/flat-bottomed funnel containing filter paper
Buchner flask/side-arm flask connected to vacuum pump
Which alcohol can be oxidised by acidified potassium dichromate(VI) but cannot
be dehydrated by heating with concentrated sulfuric acid?
A 2,3-dimethylbutan-2-ol
B 2,2-dimethylpropan-1-ol
C 2-methylpropan-2-ol
D pentan-3-ol
B
Describe how the students would use this apparatus to collect a sample of
ethanol.
Include in your answer the functions of the parts of the apparatus labelled
A, B and C. 6 marks
Stage 1
* Turn on the water.
* Heat the flask, with a Bunsen burner.
* This causes water and ethanol vapours to be produced.
Stage 2
* Vapours pass up the fractionating column A.
* Water and ethanol are separated in column A.
* Water condenses back into the flask in column A.
Stage 3
* Observe the thermometer at B to keep the temperature at or below the boiling point of
ethanol. Only ethanol vapour (with a little water) passes into the condenser.
* Use the condenser at part C to cool the vapours and condense the ethanol back into a
liquid.
