Definition in HKDSE chemistry:
1. Isotopes
are different atoms of the same element having the same number of protons but
different number of neutrons.
2.
Standard enthalpy change of neutralization
is the enthalpy change when an acid reacts with an alkali to form one mole of
water under standard conditions.
3.
Standard enthalpy change of formation
is the enthalpy change when one mole of the substance is formed from its
constituent elements in standard states under standard conditions.
4.
Standard enthalpy change of combustion
is the enthalpy change when one mole of the substance is completely burnt in
oxygen under standard conditions.
5.
Enthalpy change is the heat change (of the system) under constant pressure.
Internal energy change is the heat change (of the system) under constant volume.
6.
Hess’s law
The total enthalpy change between the initial reactants and the final products is
independent of the route by which the reaction may occur.
7.
Hydrogen bond
is the intermolecular force existed when a molecule contain an H atom attached to
a highly electronegativity atom (i.e. N, O, F) and the other molecule contain a
highly electronegativity atom (i.e. N, O, F) that provides lone pair of electrons.
8.
Structural isomerism
occurs when there are two or more compounds with the same molecular formula
but different orders of linkage of atoms (i.e. different structures)
9.
Stereoisomerism
occurs when atoms are joined in the same order but have a different spatial
arrangement.
1
10. Enantiomer
is one of the two stereoisomers that are mirror images of each other that are nonsuperimposable.
11. Electronegativity
is the power of an atom in a molecule to attract bonding elections.
12. Relative atomic mass
is the average isotopic mass of the natural isotopes / average mass of an atom of
the element on the 12C (=12.00) scale.
13. Standard solution
is a solution with known molarity.
14. Standard condition
⚫ Pressure: 1 atm
⚫ Temperature: 25°C or 298 K
⚫
Concentration (if in solution): 1.0 mol dm-3
⚫
Substances in standard states (normal physical state of their most stable form
at 298 K and 1 atm)
15. Basicity
is the number of ionizable hydrogen atoms per acid molecule.
16. Cracking
is a process breaking down the large (organic/hydrocarbon) molecule into smaller
molecules.
17. Catalyst
can speed up a reaction by providing an alternative pathway with lower activation
energy.
18. Markovnikov’s rule
states that the major product is formed when H atom of HX (where X=halogen) is
added to the C (of C=C bond) with more H atoms attached, while the halogen atom
is added to the C (of C=C bond) with less H atoms attached.
2
19. Addition polymerization
is a reaction in which monomer molecules join together repeatedly to form
polymer molecules without elimination of small molecules.
Topic 1 Planet Earth
1. Limestone, chalk and marble are different forms of calcium carbonate.
2. Thermal decomposition of calcium carbonate
⚫ Flow chart:
+CO2
Ca(OH)2
CaCO3
heat
+ H2O
CaO
⚫
CaCO3 + H2O + CO2 → Ca(HCO3)2
Topic 2 Microscopic World I
1.
2.
Atomic number = number of protons
Mass number = number of protons + number of neutrons
Topic 3 Metals
1. Extraction of metals
Method
2.
Metal
Remarks
Electrolysis of molten K, Na, Ca, Mg, ⚫
ore
Al
⚫
Expensive
Can extract other less reactive metal
heating metal oxide Zn, Fe, Pb, Cu
⚫
Metal ore is converted to oxide first
with carbon
⚫
FeS2 + O2 → Fe2O3 + SO2
heating metal oxide Hg, Ag
alone
/
Panning
/
Au
Reactions of metals (K → Hg) with oxygen
⚫ 3Fe + 2O2 → Fe3O41
⚫ Iron: yellow sparks
⚫ Magnesium: intense white light
For other reactions, Fe will not be oxidized to Fe3+ easily unless using strong oxidizing agent like
H2SO4(l)
1
3
3.
Reactions of metals (K → Ca) with water
⚫ Metal hydroxide and hydrogen gas are formed
⚫ Ca(OH)2 is slightly water-soluble
4.
Reactions of metals (Mg → Fe) with steam
⚫ Metal oxide and hydrogen gas are formed
⚫ 3Fe(s) + 4H2O(g) → Fe3O4 + 4H2(g)1
5.
Reactions of metals (Ca→Pb) with dilute HCl/H2SO4
⚫ K/Na → Explosion
⚫ Form metal chloride/sulphate + hydrogen gas
⚫ Some ionic compound is insoluble: PbCl2/PbSO4/CaSO4
⚫ H+(aq) is not strong enough to further oxidize Fe2+(aq) to Fe3+(aq)
6.
Reactions of metals with dilute HNO3
⚫ Colourless NO(g) is released and reacts with O2(g) readily to form brown
NO2(g)
⚫ Dilute HNO3 exhibits oxidizing properties (can react with Cu)
7.
Reactions of metals with concentrated HCl
⚫ Concentrated HCl still exhibit acidic property (does not react with Cu)
⚫ Reaction rate is higher due to higher concentration
8.
Reactions of metals with concentrated H2SO4.
⚫ Colourless, pungent SO2(g) is produced.
⚫ Concentrated H2SO4 exhibits oxidizing properties. (can react with Cu or Ag)
9.
Reaction of metals with concentrated HNO3.
⚫ Brown NO2(g) is produced.
⚫ Concentrated HNO3 exhibit oxidizing properties (can react with Cu or Ag)
Summary
HCl
H2SO4
HNO3
dilute
conc.
dilute
conc.
dilute
conc.
Mg(s)
H2(g)
H2(g)
H2(g)
SO2(g)
NO(g)
NO2(g)
Cu(s)
✗
✗
✗
SO2(g)
NO(g)
NO2(g)
4
10. Displacement reactions
⚫ A metal will always displace (ions of) a less reactive metal from a solution of
the compound of the less reactive metal
11. Reduce oxide of a less reactive metal by heating it with a more reactive metal
⚫ It is not burning as burning involves oxygen gas.
⚫ e.g. CuO + Mg → Cu + MgO
⚫ e.g. Fe2O3 + 2Al → 2Fe + Al2O3 [Thermite reaction in which large amount
of heat is released. It is for repairing railway.]
12. Empirical formula
gives the simplest whole number ratio of atoms or ions present in the compound
13. Molecular formula
gives the actual number of atoms in a molecule. However, it does not show the
order of linkage of the atoms (structure).
14. Rust
⚫
⚫
Reddish brown hydrated iron(III) oxide (Fe2O3 • nH2O)
Fe(s) → Fe2+(aq) +2e-
⚫
1
⚫
Fe2+(aq) +2OH- → Fe(OH)2(s)
⚫
⚫
⚫
4Fe(OH)2(s) + O2(aq) + 2H2O → 4Fe(OH)3(s)
4Fe(OH)3(s) gradually changes to Fe2O3 • nH2O
Overall: 4Fe(s) + 3O2(g) + 2nH2O(l) →2Fe2O3 • nH2O(s)
O2(aq) + H2O(l) + 2e- → 2OH-(aq)
2
15. Factors that speed up rusting
⚫ Presence of acidic pollutants
⚫ Presence of soluble ionic compounds
⚫ High temperature
⚫ Attachment of less reactive metals to iron
⚫
Presence of electrolytes
Scratched, bent or sharp area of an iron-made object
5
16. Methods to prevent rusting
Method
Mechanism
Advantage
⚫
Painting
cheap
⚫
Scratched off
easily
Coating with
⚫
lasts long
plastic
⚫
looks good
⚫
does not fall off
⚫
⚫
greasing
has lubricating
⚫
⚫
effect
The added layer prevents the
iron object from contacting
More expensive
Example
Bridges, ships,
fences, car bodies
Coat hangers, paper
than painting
like paint or plastic
Oiling or
Galvanizing
Disadvantage
Not ‘once and
clips
Moving parts of
for all’
machines (bicycle),
Dirt would
woodworking tools
stick to oil or
grease
⚫
The iron is still
⚫
protected in case
with air and water
Zinc ions are
Galvanized iron plate
poisonous
used in construction,
the zinc coating is
buckets
damaged
⚫
⚫
Tin-plating
Tin is corrosion
⚫
Rusting will
‘Tin cans’ for storing
resistant
occur more
food
Tin and tin ions
quickly when
are not poisonous
the tin coating
is damaged
⚫
Electroplating
Beautiful shiny
⚫
Expensive
appearance
the negative terminal (anode) of
⚫
Convenient
Water taps, car
bumpers
⚫
Not applicable
Car bodies,
to many objects
underground water
Cathodic
an electric source is connected
protection
to the iron object, supplying
pipelines, storage
electrons to prevent rusting
tanks, steel pier legs
⚫
effective
⚫
The sacrificed
Galvanized iron, zinc
a more reactive metal in contact
metal needs
blocks attached to the
Sacrificial
is sacrificed to form ions; this
replacement
ship hull, magnesium
protection
would prevent iron from
from time to
blocks connected to
forming iron(II) ions
time
underground
pipelines
Iron is alloyed with carbon,
⚫
chromium, nickel and
Using alloys of
manganese which are corrosion
iron
resistant
Beautiful
⚫
Most expensive
Cookware, cutlery
appearance
⚫
Very effective
[Stainless steel is covered with
tough Cr2O3 layer]
6
Topic 4 Acids and Bases
1. Reactions of acid
A. with metals
HCl
H2SO4
HNO3
dilute
conc.
dilute
conc.
dilute
conc.
Mg(s)
H2(g)
H2(g)
H2(g)
SO2(g)
NO(g)
NO2(g)
Cu(s)
✗
✗
✗
SO2(g)
NO(g)
NO2(g)
B.
with metal carbonate/hydrogencarbonate
⚫ CO32-(aq) + 2H+(aq) → CO2(g) + H2O(l)
⚫ HCO3-(aq) + H+(aq)→ H2O(l) +CO2(g)
C.
with metal oxide/hydroxide
⚫
D.
Form salt and water
with ammonia
⚫ Form ammonium salt
Summary (Non-redox reaction)
HCl
dilute
Metal carbonate/
hydrogencarbonate
H2SO4
conc.
conc.
dilute
conc.
metal salt + CO2(g) + H2O(l)
Metal
oxide/hydroxide
2.
dilute
HNO3
metal salt + H2O(l)
Reactions of alkali
A.
Alkali with acids
⚫ Neutralization (Form salt and water only)
B.
NaOH / KOH with ammonium
⚫ NH4+ + OH- → NH3 + H2O
⚫
Upon warming the solution, pungent gas which turns moist red litmus
paper blue evolved.
7
C.
Alkali with aqueous solution of metal ions
KOH(aq) / NaOH(aq)
NH3(aq)
Mg2+
white
white
Fe2+
dirty green
dirty green
reddish brown
reddish brown
Cu2+
blue
blue [redissolve in excess to give a
deep blue solution]
Ag+
brown [Ag2O]
brown [Ag2O][redissolve in excess]
Al3+
white[redissolve in excess]
white
Zn
2+
white[redissolve in excess]
white[redissolve in excess]
Pb2+
white[redissolve in excess]
white
3+
Fe
*Ions that redissolve mostly form colourless solution unless other specified.
3.
pH = -log[H+(aq)]
4.
Strong acid completely ionizes in water to give H+(aq)
Weak acid partly/incompletely ionizes in water to give H+(aq)
Strong alkali complete ionizes/dissociates in water to give OH-(aq)
Weak alkali partly/incompletely ionizes/dissociates in water to give OH-(aq)
Topic 5 Fossil Fuels and Carbon Compound
1. Complete combustion of organic compounds gives CO2(g) and H2O(l).
Combustion is an exothermic reaction.
2.
Acid Rain
⚫ Rain water is naturally acidic to the presence of CO2 in air. This in NOT acid
rain. Carbonic acid is formed when CO2 dissolve in water.
⚫
⚫
Acidic gases such as SO2(g) and NO2(g) dissolve in rain water to give a more
acidic solution → formation of acid rain
⚫ SO2(g) + H2O(g) ⇌ H2SO3(aq)
⚫
⚫
CO2(g) + H2O(l) ⇌ 2H+(aq) +CO32-(aq)
2NO2(g) + H2O(l) → HNO3(aq) + HNO2(aq)
Removal of pollutants by installing scrubber in incinerators/factories.
⚫ Ca(OH)2(aq) + SO2(g) → CaSO3(s) + H2O(l)
8
⚫
Removal of pollutants by installing catalytic converter in car exhaust system.
⚫ 2CO(g) + 2NO(g) → 2CO2(g) + N2(g)
[Catalyst: Platinum(Pt)]
⚫ CO(g) + O2(g) → CO2(g)
[Catalyst: Platinum(Pt)]
⚫
3.
2
O2(g) → 8CO2(g) + 9H2O(l)
[Catalyst: Platinum(Pt)]
Alkene is usually produced. H2 and C may also be formed.
Catalyst: Pumice stone OR Al2O3 OR Broken pieces of unglazed porcelain
Reactions of alkanes
A. Combustion (Complete/Incomplete)
B.
Substitution reaction with halogens (Cl2/Br2)
⚫ A mixture of produces is obtained
⚫ Condition: UV light or diffused sunlight
⚫ Red-orange Br2 in organic solvent is decolorized.
⚫ For reaction of CH4 + Br2 :


5.
25
Cracking
⚫ Two types of cracking: Thermal cracking and catalytic cracking
⚫
⚫
4.
C8H18(l) +
Excess CH4 → CH3Br as major product
Excess Br2 → CBr4 as major product
Reactions of alkenes
A. Combustion (usually incomplete due to presence of C=C bond)
B.
C.
Addition reaction with halogen (Br2/Cl2) in organic solvent
Addition reaction with cold, dilute and acidified / alkaline KMnO4 solution
 A diol is formed.
 In acidic medium, colour change from purple to colourless [∵Mn2+(aq)]

D.
E.
In alkaline medium, colour change from purple to brown [∵MnO2(s)]
Alkene does NOT react with acidified K2Cr2O7(aq)
Addition polymerization
Topic 6 Microscopic World II
1.
Some molecules have non-octet structure
A. BF3 → Boron has 6 outermost shell electrons
B. PCl5 → Phosphorus has 10 outermost shell electrons
C. SF6 → Sulphur has 12 outermost shell electrons
9
2.
There are different 3-D shapes of molecules
A. Tetrahedral
B. Trigonal pyramidal
C.
D.
E.
V-shaped
Trigonal bipyramidal
Octahedral
Topic 7 Redox Reaction, Chemical Cells and Electrolysis
1.
Hydrogen-Oxygen fuel cell
⚫ Three compartments separated from one another by two electrodes made of
porous nickel or platinum electrodes
 Anode compartment (fuel): Hydrogen
 Cathode compartment (oxidant) : Oxygen
⚫
2.
 Central compartment (electrolyte): Concentrated KOH(aq) [alkaline]
Equations
 Anode: H2(g) + 2OH-(aq) → 2H2O(l) + 2e Cathode: O2(g) + 2H2O(l) +4e- → 4OH-(aq)
 Overall: 2H2(g) + O2(g) → 2H2O(l)
Factors affecting results of electrolysis
⚫ Position of ions in the E.C.S.
 Electrolysis of dilute H2SO4(aq) using platinum electrodes
➢ H+(aq) and OH-(aq) will preferentially discharge

⚫
⚫
Electrolysis of CuSO4(aq) using carbon electrodes
➢ Cu2+(aq) and OH-(aq) will preferentially discharge
Concentration effect
 Electrolysis of concentrated sodium halide solution using graphite
electrodes [Platinum should not be used as it will be attacked by Cl2(g)]
➢ H+(aq) and Cl-(aq) will preferentially discharge
➢ Note that Cl2(g) formed may dissolve in remaining NaOH(aq)
Nature of electrode
 Electrolysis of brine using mercury as cathode and graphite as anode
➢

Sodium will preferentially discharge at mercury cathode to form
sodium amalgam
Electrolysis of CuSO4(aq) using copper electrodes
➢ Cu(s) and Cu2+(aq) will preferentially discharge
10
Topic 8 Chemical Reaction and Energy
1. All state symbols should be clearly shown
2. Definitions refer to P.1
3.
Enthalpy change of an exothermic reaction is negative
Topic 9 Rate of Reaction
CHANGE in concentration of a product or reactant
1.
Reaction rate =
2.
Instantaneous rate = The rate at a particular instant of the reaction
It can be found by finding the slope of tangent drawn at a particular time in the
concentration-time graph
3.
Average rate =
4.
Under the same temperature and pressure:
⚫
5.
TIME
Total change in amount of a product or reactant
Total time taken or time interval for the reaction
No. of moles of gas =
volume of gas
molar volume of gas (24.0 dm3 mol−1 under room condition)
Avogadro’s Law
states that all gases that have equal volumes have the same number of (mole of)
molecules under same temperature and pressure
6.
Different techniques to follow the progress of the chemical reactions
A. Titrimetric analysis
I.
At a regular time interval, withdraw a fixed volume of reaction mixture
by pipette, quench the withdrawn reaction mixture with large amount of
cold distilled water to stop the reaction by lowering the temperature and
the concentration of the reactants.
Titrate the reaction mixture against certain standard solution with certain
indicator if necessary
III. Record the titre added and repeat the titration at least 3 times.
IV. The concentration of the reactant left in the reaction can be determined
II.
B.
By measuring the volume of gas formed during the reaction by a gas syringe
over a period of time
C.
By measuring the decrease in mass during the reaction by an electronic
balance over a period of time

The mass of hydrogen gas is too small to be measured
11
D.
By measuring the time taken for the disappearance of the cross mark.
The rate is inversely proportional to the time for disappearance of the cross
mark.

E.
S2O32-(aq) + 2H+(aq) → SO2(g) + H2O(l) + S(s)
By measuring the absorbance of the reaction mixture over a period over a
period of time
Topic 10 Chemical Equilibrium
1. Kc, equilibrium constant is calculated by using concentration
2. Concentration of solid or liquid is considered as constant in heterogenous
condition
3. Concentration of liquid is considered as constant if it is very large
4.
5.
Investigate the qualitative effects of pH on chemical equilibrium systems such as
➢ Br2(aq) + H2O(l) ⇌ HOBr(aq) + HBr(aq) [brown → colourless]
➢ Cr2O72-(aq) + H2O(l) ⇌ 2CrO42-(aq) + 2H+(aq) [orange → yellow]
Investigate the equilibrium of the following reactions to study the shift of
equilibrium position upon changing concentration or temperature
➢
➢
SCN-(aq) + Fe3+(aq) ⇌ Fe(SCN)2+(aq) [yellow → bloody red]
Co2+(aq) + 4Cl-(aq) ⇌ CoCl42-(aq) [pink → blue] H>0
Topic 11 Chemistry of Carbon Compounds
1. Interconversion of carbon compounds
Ketone
Dihaloalkane
Halogen (X2)
Halogen (X2)
UV light
Dark
1. NaBH4
K2Cr2O7(aq)/H+(aq)
1. PCl3
1. NaOH(aq), Heat
2. H+(aq)
Heat
2. NH3
2. H+(aq)
K2Cr2O7(aq)/H+(aq)
H2SO4(l),
Alkane
Al2O3, heat
Alkene
Amide
Heat
Heat
Alcohol
Carboxylic acid
1.LiAlH4/dry ether
H2, Pt (Ni),
2. H+(aq)
Heat
HX
NaOH(aq),
HX(PX3)
heat
Halogen (X2)
UV Light
Haloalkane
K2Cr2O7(aq)/H+(aq)
Heat
1. NaOH(aq),
ROH
Heat
H2SO4(l), heat
2. H+(aq)
1.LiAlH4/dry ether
1.LiAlH4/dry ether
2. H+(aq)
2. H+(aq)
Aldehyde
Ester
12
2. Common carbon compounds
⚫ Structure of aspirin (acetylsalicyclic acid)
Functional groups: Ester, carboxylic acid and benzene
⚫
⚫
Detergents
Soapy detergent
Soapless detergent
Long hydrophobic hydrocarbon tail
Ionic hydrophilic head
Long hydrophobic hydrocarbon tail
Ionic hydrophilic head
⚫ Carboxylate head
Alkaline hydrolysis of oil/fat
(Saponification)
⚫ Sulphonate head
⚫ Sulphate head
Derived from petroleum
Nylon
Nylon-6,6
Number of carbon in carboxylic acid
Number of carbon in amine group
Contain amide linkages
⚫
Polyester
Contain ester linkages
⚫
Functional groups present in fats, oils and polypeptide
Fats/Oils: Ester
Polypeptide: Amide
13
Topic 12 Patterns in the Chemical World
1. Variation in behaviour of the following oxides in water
Na2O
MgO
Al2O3
Predominantly
Ionic
Ionic
Giant Ionic structure
Basic
2.
SiO2
P4O10
SO2
Cl2O
Covalent
Giant
Covalent
Structure
Amphoteric
Simple molecular structure
Acidic
Chemical reactions
⚫ Na2O(s) + H2O(l) → 2NaOH(aq)
⚫ Na2O(s) + 2HCl(aq) → 2NaCl(aq) + H2O(l)
⚫
MgO(s) + H2O(l) → Mg(OH)2(s)
⚫
⚫
⚫
⚫
MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(l)
Al2O3(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2O(l)
Al2O3(s) + 2NaOH(aq) + 3H2O(l) → 2NaAl(OH)4(aq) [Sodium aluminate]
SiO2(s) + 2OH-(aq) → SiO32-(aq) + H2O(l)
⚫
⚫
⚫
⚫
P4O10(s) + 6H2O(l) → 4H3PO4(aq) [Phosphoric(V) acid]
P4O10(s) + 12NaOH(aq) → 4Na3PO4(aq) + 6H2O(l)
SO2(g) + H2O(l) → H2SO3(aq) [Sulphuric(IV) acid/ Sulphurous acid]
SO2(g) + 2NaOH(aq) → Na2SO3(aq) + H2O(l)
⚫
⚫
Cl2O(g) + H2O(l) → 2HOCl(aq) [Chloric(I) acid / Hypochlorous acid]
Cl2O(g) + 2NaOH(aq) → 2NaOCl(aq) + H2O(l)
Elective – Industrial Chemistry
1. Rate equation
Rate = k[A]x[B]y
2.
Arrhenius equation
log k = log A -
3.
𝐸𝑎
2.3𝑅𝑇
where A is Arrhenius constant
Enzymes produced by yeast catalyse the conversion of sugars to ethanol. The
process is fermentation.
C6H12O6 → 2C2H5OH + 2CO2
14
4.
Catalysts
Equation
-
2I (aq) +
Catalyst
S2O82-(aq)
2-
→ I2(aq) + 2SO4 (aq)
CH3COCH3(aq) + Br2(aq) → CH3COCH2Br(aq) + HBr(aq)
H+(aq)
2H2O2(aq) → 2H2O(l) + O2(g)
MnO2(s)
2SO2(g) + O2(g) ⇌ 2SO3(g)
V2O5(s)
2MnO4-(aq) + 5C2O42-(aq) +16H+(aq)→ 2Mn2+(aq) + 10CO2(g) + 8H2O(l)
5.
Fe2+(aq) or Fe3+(aq)
⚫
⚫
⚫
⚫
Chemically unchanged at the end of the reaction
Needed in very small amounts
Very specific in action
Improved catalytic effect as the surface area increases
⚫
Poisoned by small amounts of impurities
Mn2+(aq)
Haber process
⚫ N2(g) + 3H2(g) ⇌ 2NH3(g)
Pressure:
Temperature:
Catalyst:
⚫
200 atm
450℃
Finely divided Fe
Raw materials for H2 (feedstock): natural gas, coal or naphtha

Steam reforming of natural gas
CH4(g) + H2O(g) ⇌ CO(g) + 3H2(g) [syngas/synthetic gas]
Pressure:
10-20 atm
Temperature:
700-1000℃
Catalyst:
NiO

Shift reaction
CO(g) + H2O(g) ⇌ CO2(g) + H2(g)
Temperature:
about 600 K
Catalyst:
Iron oxide
Note that CO2(g) formed is removed by scrubbing

H2 can be obtained from cracking of petroleum or electrolysis of brine
15
⚫
Flow diagram for the Haber process
N2
H2
Recycling
Pump
Purifier and
Drier
Compressor
Heat
Exchanger
Storage
Tank
Condensor
Catalytic
Chamber
⚫
Importance of Haber Process

Conversion to nitric(V) acid (Ostwald Process)
◆ 4NH3(g) + 5O2(g) ⇌ 4NO(g) + 6H2O(g)
Pressure:
8 atm
Temperature:
900℃
Catalyst:
Pt
◆
◆

increases step by step
Conversion of ammonia to fertilizer
◆ NH3(aq) + HNO3(aq) → NH4NO3(aq) [Ammonium nitrate]
◆
◆
6.
2NO(g) + O2(g) ⇌ 2NO2(g)
4NO2(g) + O2(g) + 2H2O(l) → 4HNO3(aq)
The oxidation
number of nitrogen
2NH3(aq) + H2SO4(aq) → (NH4)2SO4(aq) [Ammonium sulphate]
Conversion to urea
 2NH3(aq) + CO2(g) → H2NCOONH4(aq)
 H2NCOONH4(aq) → (NH2)2CO(aq) + H2O(l)
The importance of the chloroalkali industry
⚫ Electrolysis of brine gives chlorine gas, hydrogen gas and sodium hydroxide
solution
H2
Margarine, rocket fuel, fertilizers and HCl
Cl2
Sterilize swimming pool, PVC, solvent, HCl and bleach
NaOH
Soaps, drain cleaner, neutralize acidic effluents and bleach
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⚫
Mercury flowing cell
⚫
Membrane cell
⚫
Membrane cells do not use poisonous mercury and requires a lower voltage
to operate than the flowing mercury cell. Therefore, it is more energyefficient and causes less environmental impact.
7.
Production of methanol
⚫ Methanol is an important single-carbon compound that can act as feedstock
to synthesize other carbon compounds such as methanal, ethanoic acid etc.
⚫
Methanol can also be used as fuel and solvent.
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⚫
Manufacturing of methanol via syngas
 Steam reforming of methane to give syngas
 Water-gas shift reaction to adjust hydrogen to carbon monoxide ratio

Compression of syngas and conversion to methanol
◼ CO(g) + 2H2(g) ⇌ CH3OH(g)
Pressure:
50-100 atm
Temperature:
250℃
Catalyst:
Cu/ZnO/Al2O3
◼
8.
Distillation to obtain pure methanol
Green chemistry
⚫ Common principles
 Maximizing atom economy





⚫
Waste prevention
Use less hazardous chemical synthesis
Produce safer chemical products
Energy efficiency (e.g. Use catalyst)
Use renewable raw material
Manufacturing acetic acid (ethanoic acid)
 Use to produce PET (water bottles), PVA (glues) and table vinegar
 Fermentation
 Oxidation of naphtha or butane



Wacker process
Carbonylation of methanol
Monsanto process and CATIVA process
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