Transcript Slide 1

SALT
EXAMPLES :
replace
Metal ion
Sodium chloride
replace
Ammonium ion
Ammonium chloride
SALTS: ANION PART COMES FROM THE ACID
CATION PART COMES FROM BASES
Common Cations
Na+
Ca2+
Mg2+
K+
Al3+
Zn2+
NH4+
Pb2+
Common Anions
(parent acids)
Metal
ion
Sulfate
salts
+ H2SO4
Chloride
salts
+ HCl
Carbonate
salts
+ H2CO3
Nitrate
salts
+ H2NO3
Na +
Mg 2+
Na2SO4
MgSO4
NaCl
MgCl2
Na2CO3
MgCO3
NaNO3
Mg(NO3)2
Cu 2+
Al 3+
CuSO4
Al2(SO4)3
CuCl2
AlCl3
CuCO3
Al2(CO3)3
Cu(NO3)2
Al(NO3)3
All nitrate salts ; soluble salts
Barium
nitrate,
Calcium
nitrate,
Silver
nitrate,
Iron(III)
nitrate,
Al(NO3)3
Ba(NO3)2
Ca(NO3)2
AgNO3
Fe(NO3)3
Lead(II)
nitrate,
Potassium
nitrate,
Sodium
nitrate,
Copper(II)
nitrate,
Pb(NO3)2
KNO3
NaNO3
Cu(NO3)2
Aluminium
nitrate,
NO3-
All
salts ; soluble salts
Ammonium
carbonate,
Potassium
carbonate,
Sodium
carbonate,
Potassium
sulphate,
Ammonium
sulphate,
(NH4)2CO3
K2CO3
Na2CO3
K2SO4
(NH4)2SO4
Potassium
nitrate,
Sodium
nitrate,
Potassium
chloride,
Sodium
chloride,
KNO3
NaNO3
KCl
NaCl
All carbonate salts ; insoluble salts
Magnesium
carbonate
Calcium
carbonate
Silver
carbonate
MgCO3
CaCO3
Ag2CO3
Other names[hide]
Silver(I)Carbonate
Copper(II)
carbonate
Zinc
carbonate
Manganese(II)
carbonate
CuCO3
ZnCO3
MnCO3
Potassium
carbonate
Sodium
Carbonate
K2CO3
Na2CO3
Ammonium
carbonate
(NH4)2CO3
CO32-
All SO42-, Cl- salts ; soluble salts
Silver(I)
Chloride
Lead(II)
Chloride
AgCl
PbCl2
Mercury(II)
Chloride
Cl-
HgCl2
Lead(II)
sulphate
Calcium(II)
sulphate
PbSO4
CaSO4
Barium
sulphate
BaSO4
SO42-
Iron(II)
Chloride
Magnesium
Chloride
Zinc
Chloride
Sodium
chloride,
FeCl2
MgCl2
ZnCl2
NaCl
Copper(II)
Chloride
Copper(II)
sulphate
Aluminium(II)
sulphate
CuCl2
Potassium
chloride,
CuSO4
Al2(SO4)3
KCl
SO4
NO3-
Cl-
2-
PbSO4
CaSO4
BaSO4
AgCl
PbCl2
CO32-
CLASSIFICATION OF SALTS
PREPARATION OF SALTS
odium ,Na+ salts
otassium, K+ salts
mmonium, NH4+ salts
PREPARATION OF SOLUBLE SALTS
[ SODIUM SALTS / POTASSIUM SALTS / AMMONIUM SALTS ]
EXAMPLE
PREPARATION OF POTASSIUM CHLORIDE
H
Cl
–
K
–
.
OH
K
Cl
LET’S DO THIS:
PREPARATION OF POTASSIUM CHLORIDE
APPARATUS : Pipette 25mL, Burette 50mL, Conical Flask 250mL
MATERIALS : Potassium hydroxide 1.0 M, Hydrochloric acid 1.0 M, Phenolphthalein
Use a pipette to
transfer 25.0 cm3 of
potassium
hydroxide solution
to a conical flask.
Add 2 to 3 drops of
Colourless KOH
turn to pink.
Fill a burette
with
hydrochloric
acid and
record the
initial
burette
reading.
Record the burette
reading to 2d.p
Slowly adding the
acid into the conical
flask and swirl until the indicator
turns from pink to
colourless. Record
the volume of acid
used. (V cm3)
Record the final burette
reading to 2d.p
PREPARATION OF POTASSIUM CHLORIDE
START OVER AGAIN BUT WITHOUT INDICATOR :
To get the pure and neutral salt solution
Pipette 25.0 cm3
of the same
potassium
hydroxide solution
into a conical
flask.
Do not add any
indicator.
From the
burette, add
exactly V cm3
of hydrochloric
acid to the
alkali and
swirls and
shake well.
HEATING/EVAPORATE
COOLING
FILTRATION
DRY
Solution salt contains
impurities continuous with
recrystallisation process
PREPARATION OF SOLUBLE SALTS
[ OTHER SALTS EXCEPT Na+, K+, NH4+]
Metal/ metal oxide/
metal carbonate
Pour 50 cm3 of sulfuric acid
into a beaker. Warm the acid
Use a spatula to add
Glass rod copper(II) oxide powder bit by
bit into the acid. Stir the
Acid
mixture well. Continue adding
copper(II) oxide until some of
it no longer dissolves (excess
unreacted metal)
See the change of metal solid
colour and dissolve
Excess
unreacted metal
(residue)
Evaporating
basin with salt
solution (filtrate)
Solution salt contains
impurities continuous with
recrystallisation process
HEATING/EVAPORATE
Salt
solution
Evaporating
basin
COOLING
FILTRATION
Rinse
with
distilled
water
DRY
Glass rod
Salt Cystals
The crystals are filtered
and rinsed with a little
cold distilled water.
These physical characteristics:
• Regulars geometry shapes,
such as cubic or hexagonal.
• Flat faces, straight edges and
sharp angles.
• Same angle between adjacent
faces.
Filter
Paper
NEUTRALISATION
REACTION
1ST TITRATION WITH INDICATOR
FIND VOLUME OF ACID
2ND TITRATION NO INDICATOR
GET PURE SALT
PREPARATION
OF SOLUBLE
SALTS
TRANSFER TO
EVAPORATING
BASIN
HEATING/EVAPORATE
COOLING
FILTRATION
DRY
DISSOLVE SOLUTE IN
ACID
HEATING
DISSOLVE METAL IN ACID
EXCESS METAL NOT DISSOLVE
COMPLETE REACT
PREPARATION OF INSOLUBLE SALTS
[ ALL CARBONATE SALTS except Na+/K+/NH4+ ]
PbSO4 / CaSO4/ BaSO4/PbCl2/ AgCl ]
EXAMPLE PREPARATION OF LEAD(II) CHLORIDE
Pb
NO3
Na
Cl
Pb
Cl2
Na
NO3
DOUBLE DECOMPOSITION METHOD – TWO AQUEOUS SOLUTIONS/SOLUBLE SALTS WERE
MIX TOGETHER , INTERCHANGE TO PRODUCE TWO NEW COMPOUNDS WHICH ARE AN
INSOLUBLE SALT (PRECIPITATE) & AQUEOUS SOLUTION (SOLUBLE SALT).
Two aqueous solutions/soluble salts are mixed together
[one of the
solutions
contains the
cations of the
insoluble salt]
[one of the
solutions
contains the
anions of the
insoluble salt]
The ions of the two aqueous solutions above interchange to produce
two new compounds which is an insoluble salt or precipitate, and an
aqueous solution.
Mixture solutions
Filter paper
Retort
stand
Glass
rod
Precipitate
(residue)
Distilled
water
Glas
s rod
Precipitate
(residue)
Filter
funnel
Aqueous
Solution
(filterate)
Filtration : Remove solution from
precipitate
Rinse : remove other ions from
precipitate
Precipitate
/Soluble
salts
Filter paper
Dry : Dried by pressing between two
pieces of filter paper.
FLOW CHART :
PREPARATION OF
INSOLUBLE SALTS
MIX - STIR
TWO SOLUBLE SALTS
FILTRATION
REMOVE FILTRATE
RINSE
REMOVE OTHER IONS
DRY
PRESS BETWEEN FILTER PAPER
PREPARATION OF SALTS
REMEMBER : METAL IONS DISPLACE
HYDROGEN IONS IN ACID TO FORM SALTS
HCl [H+/Cl-]
Hydrochloric acid
Na+
Ca2+
Zn2+
K+
Al3+
Pb2+
NH4+
Mg2+
Cu2+
Fe3+
Fe2+
HNO3 [H+/NO3-]
Nitric Acid
H2SO4 [2H+/SO42-]
Nitric Acid
H2CO3 [2H+/CO32-]
Nitric Acid
Method/Reaction
Reason
Type of
Salts
(Metal)
Neutralisation
(Titration method)
Alkali + Acid  Salts + Water
Most salts of sodium,
potassium, and ammonium
ions are soluble.
Na+
K+
NH4+
Metal Displacement
Metal + Acid  Salts + Hydrogen
More electropositive metal
can be displaced hydrogen
ion from acid.
Ca2+
Mg2+
Al3+
Zn2+
Metal oxide + Acid  Salts + Hydrogen
Less electropositive metal
not be displaced hydrogen
ion from acid.
Mostly
Cu2+/Pb2+
/Ag+
Metal carbonate + Acid  Salts + Water +
Carbon dioxide
metal carbonate is a solid
that cannot dissolves in
water, in reaction that solid
must be added excessively
All above
except
Na+/K+/NH4+
Reactive metals are magnesium, aluminium, and zinc.
Unreactive metals are iron, lead, silver
Metal that is less reactive than hydrogen such as copper, lead
and silver will not react with dilute acid.
Soluble salts of sodium, potassium and ammonium can be
prepared by the reaction between an acid and alkali.
Metals, metal oxides and metal carbonates are solids that cannot
dissolve in water, hence during reaction these solids must be added
in excess to make sure all hydrogen ions in acid are completely
reacted. Excess solid can be then removed through filtration.
Unreactive metals such as lead (Pb), copper (Cu), and silver (Ag) cannot
react with dilute acid. So to prepare salt contains lead ions (Pb2+), copper
ions (Cu2+) or silver ions (Ag+), we must use either oxide powder or
carbonate powder only.
Impure soluble salt can be purified through crystallization process