Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Unit 22 – Assignment 2 – P3
Functional groups:
Alkene - ethene:

Primary alcohol – methanol:

Secondary alcohol – Propan-2-ol:

Aldehyde – ethanal:

Ketone – propanone:

Carboxylic acid – ethanoic acid:

Amine – methylamine:

Chemical procedures for testing functional groups
Method:
Procedure:
Test 1: For the first test, I added 1-2 drops
of the alkene to around 2cm3 of bromine
water
...
After
that I added 1-2 drops of either
primary/secondary alcohol or aldehyde
...

Test 3: For test 3, I added around 2cm 3 of
Fehling's solution number 1 to around 2cm 3
of Fehling's solution number 2
...
Then I put the
test tube in the water bath for about 5-10
minutes, make sure the water bath is at an
appropriate temperature
...
Then I put the
test tube in the water bath for about 5-10
minutes, make sure the water bath is at an
appropriate temperature
...
2M
NaOH to about 1cm3 of silver nitrate
solution
...

Test 5: For this test, I added around 1cm 3 of
carboxylic acid to a test tube, I then added
a spatula load of solid sodium carbonate to
this
...

Colour change from brown to clear
...


After doing this, a red precipitate should
appear
...


This should result with a gas forming,
bubbling through the limewater, which
forms a white precipitate
...
I then put a piece of red
litmus paper and a piece of blue litmus
paper in each test tube
...

Test 7: For this test, I added around 1cm 3 of
Brady's reagent to a test tube
...

Test 8: For the final test, I added around
2cm3 of iodine solution to a test tube
...
I then
added NaOH, until the iodine became
decolourised
...
If the
litmus paper turns from blue to red in a
solution, that means it is an carboxylic acid
...


After doing this, a yellow precipitate should
appear
...
chem
...
edu/~webspectra/irtable
...


Results:

Unit 22 – Assignment 2 – P4
Method:
Procedure:
Method 1: This method required me to add 1-2cm3 of the solution to be tested
...
2 M NaOH dropwise into the test tube
...

Method 2: This method required me to add 1-2cm3 of the solution to be tested
...
This test was carries out on two of the solutions
containing these cations: Na+, Mg2+, Ca2+, Al3+, Zn2+, Fe3-, Cu2+ and Ni2+
...
A silica rod was heated in a
Bunsen burner flame until there was no colour being produced
...

Method 4: This method required me to add around 1cm3 of dilute HNO2 and 1cm3 of dilute
AgNO3
...
We then
separately added concentrated and dilute ammonia to parts of any precipitate that was
formed, this was to test for solubility
...

Method 5: This test required me to add around 2cm 3 of dilute hydrochloric acid or HNO3,
to around 2cm3 of a solution containing the sulfate ion (SO42-)
...

Method 6: This method required to add around 2cm3 of dilute hydrochloric acid or HNO3,
to around 2cm3 of a solution containing the sulfate ion (SO42-)
...

Method 8: This method required me to add around 2cm3 of dilute hydrochloric acid to a
test tube, I then added a spatula load of solid or 1-2cm3 of the solution containing the
carbonate ion (CO32-)
...


Results:
Unknown organic:
A
B
C (cation)
C (anion)
D (anion)
E (anion)
F (anion)
F (cation)
A and B

Test carried out:
Test 3 = K+
Test 3 = Na+
Test 1 = Fe2+
Test 2 = Fe2+
Test 4 = Br
Test 8 = Co32Test 4 = Br
Test 4 = ClTest 1 = Mg2+
A = Iodide
B = Carbonate

Observation:
Pink flame
Orange flame
Green gelatinous
precipitate for both
Cream precipitate
Colourless odourless
gas
Cream precipitate
White precipitate
White precipitate

Outcome:
Kl
Na2CO3
FeSO4
FeSO4
Na2Co
NaBr
Magnesium chloride
Magnesium chloride

Unit 22 – Assignment 2 – M3
Compound A:
The IR Spectrum table shows that there was a peak between 2000-1500/cm-1
...
This describes the peak of the unknown compound
...
This proved that this compound was not a ketone
...
This proved that compound A was an aldehyde; butanal
...
This solid will then float to the top as a yellow precipitate
...
The reason for the production of the
silver mirror is because aldehydes reduce the diamminesilver(I) ion to metallic silver
...

Compound B:
The IR Spectrum table showed that there was a peak between 2000-1500/cm-1 (this is
similar to the aldehyde)
...
Compound B was then tested for ketone and the
observation for this experiment was a yellow precipitate
...
Thus proving that compound

B was the ketone propanone
...
This solid will then float to the
top as a yellow precipitate
...
Then the infrared absorption data shows that that they were both
alcohols, as the number matched the peak on the table; compound C was a primary alcohol,
whilst compound D was a secondary alcohol
...
The test for compound D resulted in
a change from orange to green, this shows that it was a secondary alcohol
...
This means that it could have been an acid
(either an alkene or an amine)
...
Then the functional group on the infrared absorption data showed
that it could have been an amine or an acid
...
Firstly, the red litmus paper was put in and
there was no change in colour
...
Thus proving that compound E was the carboxylic
acid, ethanoic acid
...
This pH paper changes colour in different pH
solutions because of the chemical flavin
...

Compound F:
After identifying most of the compounds, I could see that there were only two left, alkene
and amine
...
Then
the infrared absorption data shows the functional group matched the wave number/cm-1
was a C=C bond; this means that it would have been an alkane
...

Why bromine changes colour
Compound G:
After testing the compounds, it looked like compound G could have been ethylamine
...
A test was carried out with red litmus paper and it changed to blue; thus
proving that compound G was ethylamine
...
This pH paper changes colour in
different pH solutions because of the chemical flavin
...


Unit 22 – Assignment 2 – M4
Compound A and B – Test 1:
In order to find out what compound A and B was, I had to do numerous tests
...
The first test I did was a flame test (cation) on both
compound A and B
...
After that I put it over the flame and identified the
colour of the flame
...
When I put compound B over the flame, it
resulted in an orange flame; this shows that there was a sodium ion present
...
Whilst this is happening,
the electrons move from the ground state to the excited state
...
Whilst this occurs, light energy is release
...
For potassium, a lilac flame would be made, this is because the energy levels are
different
...
The reason for this is because the alkali
metals will not form a precipitate with sodium hydroxide

Compound C (cation and anion) - Test 5:
In order to find out what compound C was, I had to do numerous tests
...
The observation for this test was a green gelatinous precipitate
...

The second test that was carried out (Test 5) required me to add dilute HCL, compound C
and then to add barium chloride
...
After carrying out both tests, I came to
the conclusion that compound C was Fe2+SO4
...
The reason for this is because the product of the reaction
(BaSO4(s)) is a white crystalline insoluble solid
...

Ba2+ + SO42- = BaSO4(s)

Compound D – Test 8:

In order to find out what compound D was, I had to do a test
...
The observation for this test was a colourless, odourless gas bubbling through the
limewater, which later formed a white precipitate; this shows that CO 32- was also present in
compound D
...

The reason for this is because the product of the reaction (calcium carbonate) is a white
crystalline insoluble solid
...

When carbon dioxide dissolves in water, it forms carbonic acid
...
Calcium carbonate is insoluble and precipitates
...


Compound E – Test 4:
In order to find out what compound E was, I had to do a test
...
The observation for this test was a cream precipitate
...
On the other
hand, when concentrated ammonia was added to the test tube, the precipitate was not
dissolved: this shows that Br- was present in compound E
...
The reason for
this is because the product of the reaction is a cream crystalline insoluble solid
...


Compound F (cation and anion) - Test 4:
In order to find out what compound F was, I had to do numerous tests
...
The observation for this test was a white precipitate; this
shows that Mg2+ was also present in compound F
...
The
method required me to add dilute nitric acid, compound F and then to add solver nitrate
...
To test this precipitate, I added
ammonia which resulted in the precipitate being dissolved; this shows that Cl - was also
present in compound F
...

Both compound E and F are the same
...
A white precipitate was formed, the reason for this is because the product of the
reaction is a white crystalline insoluble solid
...


Unit 22 – Assignment 2 – D2

Organic compounds:
After looking at my results, and comparing my method (comparing the peak(s) on the IR Spectrum
table to the values on the infrared absorption table, to ensure accuracy), I can come to the
conclusion that they were accurate, valid and reliable
...

An alternate method for identifying the compounds, is a nuclear magnetic resonance (NMR)
spectroscopy test
...
Nuclear spin and the atom nucleus is exposed to a
magnetic field
...
The nucleus can either align itself against
the magnetic field (this causes it to be in a state of high energy), or with it (this causes it to be in a
state of low energy)
...
The nucleus will
absorb the energy and jump to a state of high energy, if it is in a state of low energy
...
, whilst the nucleus is settling to the state of low energy
...
The reason for this is
because it results in finding values for chemical shifts, which occur in different nuclei for different
compounds
...
This is due to a
number of possible errors that could have occurred during this experiment
...
If I could have compared my results to the IR
spectrum data, it would have increases the reliability of the investigation
...

For example, for the first method, mass spectroscopy would have been a much more accurate, as it
is used in industry
...
The formula of
the compound can be found by comparing the mass data with researched experimental analysis
...
This is done by spiking the analyte with the known part, this makes it easier to
identify the compound
...

For the third method, another method would be to use x-rays
...
In order to identify what the molecule is, the atoms arrangement is reconstructed by a
computer
...
If someone was to put too much or too little of one
of the solutions, then there would be an inaccuracy of ratios
...

This would cause not complete this test and for the experiment to be incomplete
...
If t does, do not add too much or too little (around 3 drops)
...

Another error that can occur in both experiments is due to eyesight
...

This would cause the identifications to be inaccurate as it would be recorded as a 'no reaction', when
it actually did occur
...
By doing this, you
can ensure that your identifications are accurate
...
Rushing the test could
also cause inaccurate identifications
...
To resolve this error, wait at least as few
minutes whilst continuously swirling the test tube to ensure that the liquids are properly mixed
...
If a
precipitate has still not appeared, then you can record the test as a 'no reaction'
...

Another error that can occur in both experiments is due to colour blindness
...
Not only is the colour change sometime slow, people
have different sensitivities to colours – not to mention colour blindness
...
The solution should
also be swirled for about a minute as the reaction may be slow and the wrong result may be
recorded
...

Another error that can occur in both experiments is due to contamination of glassware
...
Also it may
be easy to forget to rinse the glassware after the solution was transferred
...
To
resolve these errors, the glassware must be rinsed properly for about a minute, to be sure that no
residue from the last procedure affects the results in the next
...

Another error that can occur in both experiments is due to contamination of pipettes
...
Also, if after using the pipette (or several
pipettes), someone should just lay it on the desk, if that was used for a different liquid than
previously used, it would cause contamination
...
This would cause the tests to have an inaccurate outcome
...
Also, if the pipettes have been just laid on the
table and you cannot remember which liquid it was used for, put it Ito the sink and use a different
one
...




---