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Unit 8: Chemical Analysis - Coggle Diagram
Unit 8: Chemical Analysis
Paper Chromatography
Method used to
separate substances in a mixture
. You can then use this to
identify the substances.
Stationary Phase
Where
molecules can't move
Can be a
solid or a thick liquid
Mobile phase
Where
molecules can move
Always a
liquid or gas
Purity and Formulations
A
pure
substance is a substance that
only contains one compound
or
element
throughout
Using
melting
and
boiling
points to see
how pure a substance is
A
chemically pure substance
will
boil
at a
specific temperature
Impurities
in your sample will
decrease
or
increase
the
melting point
You can
test the purity
of a substance by
measuring its melting/boiling point
and
comparing it to the data
of the
pure
substance
Formulations
Formulations
are
useful mixutures
with a
precise purpose
that are made by
following a
recipe
Important in the
pharmaceutical industry
Information on
cleaning product packaging, fuels, cosmetics, fertilisers etc,
will tell you the
ratio/percentage
of all the
components
. This is the
formulation
Test for Gases
Oxygen
Glowing splint inside a test tube of oxygen
. Splint will
relight
Carbon Dioxide
Bubbling/shaking carbon dioxide into lime water
(aqueous calcium hydroxide). Solution turns
cloudy.
Makes a
precipitate
Chlorine
Chlorine
bleaches
damp litmus paper
Hydrogen
Lit splint
at the opne end of a
test tube containing hydrogen.
SQUEAKY POP.
Test for Cations
Lithium (Li+)
burns with a
crimson
flame
Sodium (Na+)
burns with a
yellow
flame
Potassium (K+)
burns with a
lilac
flame
Calcium (Ca+)
burns with a
green
flame
Test for Anions
Test for Carbonates
Dilute acid
can help
test for carbonates
Metal carbonate + acid
--> salt + water +
carbon dioxide
First add
dilute hydrochloric acid
. If carbonate ions (CO3 2-) are present
carbon dioxide will be released
and will
turn limewater cloudy
CO3 (2-)
Na2Co3 (aq)
+
2HCl (aq)
--> 2NaCl (aq) + H20 (l) +
CO2 (g)
Test for Sulphates
SO4(2-)
Add
BaCl2 + HCl
, if its a
sulphate
a
white precipitate
will form
Ba (2+) + SO4 (2-) --> BaSO4
Test for Halides
Add drops of
dilute nitric acid (HNO3)
, followed by drops of
silver nitrate solution
(
AgNO3
), to your mystery solution
[
Ag + Cl --> AgCl
]
Chloride
gives a
white
precipitate of silver chloride
[
Ag + Br --> AgBr
]
Bromide
gives a
cream
precipitate of silver bromide
[
Ag + I --> AgI
]
Iodide
gives a
yellow
precipitate of silver iodide
Flame Emission Spectroscopy
Since
no two ions have the same charge and electron arrangement,
different ions emit
different wavelengths of light
Used to identify different metal ions
in a solution accurately and to
find their concentrations
Each
ion produces a different pattern
of wavelengths and has a
different line spectrum
The
intensity of the spectrum
indicates the
concentration
of
that ion
in the solution