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Summary of Chapter 29 OCR A Chemistry
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l l l O l l 2 IChapter 29 -
Chromatography and
spectroscopy
29 I .
Chromatography and functional group
analysis
stationary phase -
does not move and is
normally a solid / liquid supporting a solid
does
mobile phase move and is
normally a liquid /gas
-
,
chromatography -
separation of a mixture by passing it in solution 1 suspension through a medium
in which the components move at different rates
polar -
a molecule with an overall
charge
non polar a molecule with no overall
-
charge
-
retardation factor the distance travelled solute compared to the solvent
by a
-
retention time The time taken for
gas 1 liquid
a to pass
through the column
-
adsorption - The attraction of an atom to the surface of another substance
absorption - when atoms enter another bunny phase such as a solid 1 liquid
polar t time to travel
Thin
layer chromatography ( TLC)
,
up chromatogram
→
quick and inexpensive
→
indicates how components are in a mixture
many .
→
TLC
plate coated with a thin layer of solid Absorbart substance ( e.g , silica)
→
Absorbant the
is
stationary phase
different components different affinities for
→
have the absorbent and bird with
differing strengths
to its surface
→
adsorption process where solid silica holds different substances to its surface
-
Retention factor (Rf) = distance moved by the component
distance moved by the solvent front
→
The Sowles are separated differences in their Attraction to the
by the
stationary
and the mobile phase ( one will have a high adsorption property) .
phase polar ( the phase)
→
one adsorb are and the other non polar ⇒ souses separate by polarity
-
→
Separation measured difference far the
by measuring the in how solute travels compared
to ( Retardation factor)
the solvent or
by how
quickly the saute travels
through the
chromatograph ( Retention time)
→ values can be compared to known values of grandam solutions to
identify the solute
Mobile phase polar ( alkane) / solvent ( water 1 alcohol)
tonAdsorbent
°
- -
polar
surface ( silica 1 Aluminium Oni de)
stationary phase
°
Explain how souses are separated in TLC .
↳ with a non -
polar mobile phase
→
polar stationary phase → T polarity of solute r adsorption & will travel slowest up
chromatograph
→
non have t adsorption to
polar mobile phase → non polar so hues
stationary
-
-
phase but will be t sombre in the morale phase so wi u travel
quicker up the
chromatograph .
↳ with a polar mobile phase
→
t commonly used
t whilst less polar molecules
polarity of the
→
solute it travels up the
, quicker chromatograph
would travel Rowen .
, Industry stationary :
Sia IA Koz
-
,
mobile -
solvent
Colourless Samples view under UN
light
°
:
.
°
In fume cupboard :
A A Stained
.
.
by his hydria
Iodine crystals beaker and cover Iz sublimes Iz vapour stains molecules
organic
°
. : Add to .
, spots appear as
① Take a TLC plate & draw the base line with a pencil ( 1cm from one end)
② Use a capillary tube to spot your sample onto the base line
③ Pour some solvent into a breaker (O . S on depth approx .
)
⑨ Place the plate into the beaker and cover with a watch
glass
⑤ Allow the solvent to rise up the plate until it's 1cm from the top a-
watch glass
⑥ Remove the plate and mark the solvent front with a pencil
⑦ Circle
⑧ Use w/
Any visible spots
locating agent (e.g .
ninhydrin ) to show spots
⇒
peeing
-
#
-
Tlc plate
seamer
sowenr
+ silica
gel
Spor or
substance
Gas
→
chromatography
Separating &
identifying volatile organic compounds present in a mixture .
→
stationary phase injector
Tb adsorb Port
is a .
p .
liquid -
flow →
capillary column has
F⑤⑥z→F/#aer
ed controller
onto an inert solid
liq Stationary phase
. adsorbed
support . .
→
components slow down
↳
The mobile phase is
as ineraa with the cia
they .
Y ihnairwncaryrionr ?
as such column
demurrer stationary phase
→ f soluble in stationary
column oven
I
→
Volatile t speed
mixture
injected packed with powder phase ,
it moves
→
eluent carries →
Separated based on
carrier gas
components (carrier ( me Nz ,
→
inert gas solubility
,
gas )
°
Mobile phase :
Inert gas ,
stationary phase high boiling :
liquid adsorbed onto
An inert solid support
Explain how the solutes are separated in Gas chromatography ?
→
solutes separated by their solubility in s .
P . and their B P . .
compounds with t solubility and PB Ps will travel
→
. slowest as most attracted whilst least soluble and d B . P
will pass
through the quickest .
Retention Time time from sample injected to when its recorded detector
by
→
when is the
↳ can
compare database to
to a
identify components
peak integrations → area under each peak , used to determine the core . of components
in the sample .
↳
plot a calibration curve ( peak area vs . conc .
) ⇒ external calibration
what affects retention time ?
solubility ( t soluble t time)
-
,
boiling point ( t BP 9 time condensed than gas)
-
,
as a
temperature ( 9 Hmp r time evaporated)
-
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