4.2.3 Organic Synthesis Practical Skills Flashcards
Describe how a Quickfit
apparatus is connected
Grease the joints using some petroleum
jelly on the inside of the joints before
connecting the pieces together.
In a distillation setup, why is it
necessary to have a
continuous water flow around
the condenser?
So that the water remains cool in order
for the mixture to be distilled
Describe a method that can be
used to separate immiscible
liquids
● Pour the mixture into a separating funnel and some distilled
water
● Add the stopper and invert the flask to mix the mixture
● Equalise the pressure by opening the stopper as required
● Continue shaking until there is no ‘whistle’ sound
● To collect the water in the lower layer, open the stopper and
place a beaker under the spout
● Use another beaker to collect the desired organic layer
● Shake the liquid with some drying agent
Name two drying agents
Magnesium sulphate
Calcium chloride
How to use drying agents
● Add a selected drying agent to the organic product
● If the drying agent forms clumps add some more until they
are moving freely
● Use gravity filtration to collect the dry product.
● Filtrate is the product
What does re-distillation
mean?
When a liquid is purified by using
multiple distillations
How can unsaturated
hydrocarbon be tested? What
are the observations?
Use bromine water
Add few drops of bromine water to the sample and
mix well
Positive test - bromine water turns colourless
How can unsaturated
hydrocarbon be tested? What
are the observations?
Use bromine water
Add few drops of bromine water to the sample and
mix well
Positive test - bromine water turns colourless
What are the reagents used to
test haloalkanes and what are
the observations?
Reagents - silver nitrate, ethanol and water
Observations - chloro- : white precipitate
Bromo- : cream precipitate iodo- : yellow precipitate
What are the 3 reagents that
can be used to test carbonyls?
Acidified potassium dichromate
Fehling’s solution
Tollens’ reagent
What are the 3 reagents that
can be used to test carbonyls?
Acidified potassium dichromate
Fehling’s solution
Tollens’ reagent
What are the observations
when acidified potassium
dichromate reacts with
ketones and aldehydes?
Ketones - no change
Aldehyde - turns from orange to green
colour
What are the observations
when Fehling’s solution is
reacted with ketones and
aldehydes?
Ketones - no change
Aldehyde - dark red precipitate
What are the observations
when Tollens’ reagent is
reacted with ketones and
aldehydes?
Ketones - no silver mirror
Aldehydes - silver mirror
What are the reagents that
can be used to test carboxylic
acid? What are the
corresponding observations?
Universal indicator - pH of weak acid
Reactive metal - hydrogen effervescence
Metal carbonate - carbon dioxide
effervescence
