The document describes non-metals and their properties. It discusses the physical and chemical properties of non-metals, and describes the industrial preparation of chlorine, sulfuric acid, and ammonia. It also lists common uses of non-metals like carbon, sulfur, phosphorus, chlorine, and nitrogen and their compounds.
The elements in which the valence electron enters the s orbital are called s block elements.
The elements in which the valence electron enters the p orbital are called p block elements.
The elements in which the valence electron enters the s orbital are called s block elements.
The elements in which the valence electron enters the p orbital are called p block elements.
HSSC Second year Chemistry course slides for Federal Board Pakistan, lectures by Dr. Raja Hashim Ali (also available on Youtube as lecture videos).
https://www.youtube.com/watch?v=C65jIcLKN4Q
HSSC Second year Chemistry course slides for Federal Board Pakistan, lectures by Dr. Raja Hashim Ali (also available on Youtube as lecture videos).
https://www.youtube.com/watch?v=C65jIcLKN4Q
This is a presentation file that will provide you notes, proper diagrams, short tips, mnemonics about the alkali metals.. This course is of High School of grades 11 and 12. I think it will help every type of student. Similarly, you can find some repeated and important questions.
General Principles and Processes of Isolation of Elements.pptxDamnScared
t is usually contaminated with earthly or undesired materials known as gangue. The extraction and isolation of metals from ores involves the following major steps: • Concentration of the ore, • Isolation of the metal from its concentrated ore, and • Purification of the metal.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
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Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
2. Chapter 22: Non-metals
• Describe the physical and chemical properties ofDescribe the physical and chemical properties of
non – metals.non – metals.
• Describe the industrial preparation of chlorine,Describe the industrial preparation of chlorine,
sulphuric acid and ammonia.sulphuric acid and ammonia.
• List the uses of the non – metals: carbon, sulphur,List the uses of the non – metals: carbon, sulphur,
phosphorus, chlorine, nitrogen, silicon and theirphosphorus, chlorine, nitrogen, silicon and their
compounds.compounds.
Learning Outcomes
You should be able to:
4. Chapter 22: Non-metals
Metals Non-Metals
Malleable and ductile Brittle, neither ductile nor
malleable
Good conductors of
electricity and heat
Poor conductors of heat and
electricity except graphite
Lustrous and can be
polished
Non-lustrous and cannot be
polished, except graphite and
iodine which are lustrous non-
metals
Solids at room
temperature, except
mercury
May be solids, liquids or gases at
room temperature
Differences between metals and non-metals
5. Chapter 22: Non-metals
Metals Non-Metals
Strong, tough and have
high tensile strength,
except mercury and zinc
Not strong and have low tensile
strength, except diamond and
carbon fibre
Hard and have high
density, except sodium
and potassium
Generally soft and have low
density, except diamond
High melting and boiling
points
Low melting and boiling points,
except diamond and graphite
Differences between metals and non-metals
6. Chapter 22: Non-metals
Mainly occurs in a combined state in compounds
such as water, acids and many organic substances.
Elemental hydrogen exists as diatomic molecules, H2,
which has the following properties:
•Colourless, odourless and neutral gas
•Non-conductor of electricity
•Low melting point (–259 °C) and low boiling point
(–253 °C)
Hydrogen (H)
7. Chapter 22: Non-metals
Chlorine (Cl)
Highly reactive so it never occurs in the uncombined
form in nature, mainly occurs as sodium chloride or
rock salt
Elemental chlorine exists as diatomic molecules, Cl2,
which has the following properties:
• Greenish-yellow, poisonous gas
• Non-conductor of electricity
• Denser than air
• Low melting point (–101 °C) and low boiling point (–35 °C)
8. Chapter 22: Non-metals
Oxygen (O)
Nearly half the mass of the Earth’s crust comprises
oxygen in a combined state in compounds such as
water, silicates, oxides and salts. Elemental form
exists in the air, forming 21% of air by volume.
Elemental oxygen exists mainly as diatomic
molecules, O2, which has the following properties:
• Colourless, odourless and neutral gas
• Non-conductor of electricity
• Low melting point (–218 °C) and low boiling point
(–183 °C)
9. Chapter 22: Non-metals
Carbon (C)
Found in the form of diamond (India, South Africa) and
graphite (Sri Lanka), main constituent of numerous
naturally occurring compounds such as coal, mineral
oils, carbonates, organic matter and carbon dioxide gas.
Graphite
• Black
• Soft
• Good electrical conductor
• Very high melting point (3652 °C)
• Very high boiling point (4200 °C)
Diamond
• Colourless, transparent and has a very
high refractive index
• Hardest known natural substance
• Non-conductor of electricity
• Good thermal conductor
• Very high melting point (3550 °C)
• Very high boiling point (4827 °C)
10. Chapter 22: Non-metals
Sulphur (S)
Exists as natural deposits of elemental or native sulphur,
compounds such as sulphur dioxide, zinc blende, pyrite
and gypsum. Present as hydrogen sulphide in petroleum
gases.
• Light yellow powdery solid
• Non-conductor of electricity
• Allotropes – rhombic and monoclinic sulphur
• Rhombic sulphur has a melting point of 113 °C and
boiling point of 445 °C
11. Chapter 22: Non-metals
Nitrogen (N)
Occurs combined in compounds such as sodium nitrate,
calcium nitrate and ammonium sulphate and as an
important constituent of protein. Exists as elements in
79% of the air by volume.
Elemental nitrogen exists as diatomic molecules, N2,
which has the following properties:
• Colourless, odourless and neutral gas
• Non-conductor of electricity
• Low melting point (–210 °C)
• Low boiling point (–196 °C)
13. Chapter 22: Non-metals
Solution to Quick Check 1
Strong, tough and have high tensile strength,
except mercury and zinc
Not strong and have low tensile strength, except
diamond and carbon fibre
Hard and have high density, except sodium
and potassium
Generally soft and have low density, except diamond
High melting and boiling points Low melting and boiling points, except diamond and
graphite
Metals Non-Metals
Malleable and ductile Brittle, neither ductile nor malleable
Good conductors of electricity and heat Poor conductors of heat and electricity except graphite
Lustrous and can be polished Non-lustrous and cannot be polished, except graphite
and Iodine which is lustrous non-metals
Solids at room temperature, except mercury May be solids, liquids or gases at room temperature
Return
14. Chapter 22: Non-metals
Apart from carbon, other non-metals like
oxygen, nitrogen and sulphur have
allotropes as well.
Diatomic
oxygen (O2)
Triatomic
oxygen (O3)
Sulphur has 2 allotropes : rhombic and monoclinic sulphur. Rhombic
sulphur changes to monoclinic sulphur and vice versa at temperatures
above 96 o
C and below 96 o
C respectively.
Monoclinic sulphurRhombic sulphur
15. Chapter 22: Non-metals
Metals Non-Metals
Have 1–3 electrons in the outermost
shell
Have 4–8 electrons in the outermost
shell
Lose valence electron(s) to form
cations
Gain electron(s) to form anions
or share valence electrons to form
covalent molecules
Electropositive Electronegative
Lose electrons in the valence shell
(oxidised) and make good reducing
agents
Gain electrons from other elements
(reduced) and make good oxidising
agents
Cationic metals are discharged at the
cathode during electrolysis
Anionic non-metals are discharged at
the anode during electrolysis
16. Chapter 22: Non-metals
Metals Non-Metals
Many metals displace hydrogen
from dilute acids
Do not react with dilute acids
and do not displace hydrogen
from dilute acids
Form chlorides which are
electrolytes but non-volatile
Form covalent chlorides which
are non-electrolytes but volatile
Do not combine with hydrogen,
except the reactive elemental metals
which form metal hydrides
React with hydrogen to form
stable covalent hydrides
Form basic oxides, except Cr2O3
(acidic), and Al, Zn, Pb (amphoteric)
Form acidic or neutral oxides
17. Chapter 22: Non-metals
Hydrogen: 2H2(g) + O2(g) → 2H2O(g)
Colourless,
stable liquid
Carbon: C(s) + O2(g) → CO2(g)
Colourless,
odourless gas and
an acidic oxide
In the presence of
insufficient oxygen,
carbon monoxide is
formed instead.
18. Chapter 22: Non-metals
2Cl2(g) + O2(g) → 2Cl2O(g)
Chlorine
Cl2(g) + 2O2(g) → 2ClO2(g)
The chloride oxides are acidic and
highly unstable, reacts with alkalis to
form salt.
Anhydride of hypochlorous
acid. It is an orange gas.
Reddish yellow gas, a
useful oxidising agent.
19. Chapter 22: Non-metals
Sulphur S(s) + O2(g) → SO2(g)
Nitrogen
N2(g) + O2(g) → 2NO(g)
2NO(g) + O2(g) → 2NO2(g)
Acidic oxide, colourless gas with
a pungent smell that dissolves in
water to form acid.
Colourless gas
and a toxic air
pollutant.
Reddish brown toxic gas, which has a
sharp biting odour and is an air pollutant.
20. Chapter 22: Non-metals
Reaction with metals are always a redox reaction where
the non-metal is the oxidising agent (electron acceptor)
and the metal is the reducing agent (electron donor).
Hydrogen H2(g) + 2Na(s) → 2NaH2(s)
Sulphur
Nitrogen N2(g) + 3Ca(s) → Ca3N2(s)
S(S) + Zn(s) → ZnS(s)
Hydrogen + Alkali metals → Metal hydrides
Nitrogen + Reactive metals → Metal nitrides
Sulphur + Metals → Metal sulphides
21. Chapter 22: Non-metals
Chlorine
Oxygen
3Cl2(g) + 2Al(s) → 2AlCl3(s)
O2(g) + 2Ca(s) → 2CaO(s)
3O2(g) + 4Al(s) → 2Al2O3(s)
Aluminium oxide is amphoteric and forms an
impervious layer on the aluminium metal,
protecting it from corrosion.
Chlorine + Metals → Metal chlorides
Oxygen + Metals → Metal oxides
22. Chapter 22: Non-metals
Metals
Non-metals
Semi-metal
Oxidising power increases
Electronegativityincreases
Electronegativity increases
Oxidisingpowerincreases
Nitrogen, oxygen, bromine, chlorine and
fluorine are all good oxidising agents
with fluorine being the strongest.
23. Chapter 22: Non-metals
Across the Periodic Table, the atomic radius decreases, ionisation
energy increases, and thus the electronegativity increases. The increase
in electronegativity also reflects an increase in oxidising power.
(most
(least
24. Chapter 22: Non-metals
A more reactive non-metal would be able to displace a less reactive non-
metal from its salts in aqueous solutions. For example, chlorine replaces
bromine from a solution containing bromide ions.
Cl2(g) + 2Br-
(aq)→ Br2(g) +2Cl-
(aq)
Chlorine oxidises the bromide ions by
removing an electron from it. Bromine gas
is then liberated from the solution and is
detected by its reddish-brown colour.
25. Chapter 22: Non-metals
There are several methods to collect gases from experiments
depending on the solubility and density of the gas.
Method Suitable gases
Downward displacement of water For gases which are insoluble or slightly soluble in
water
(e.g. oxygen, hydrogen, nitrogen, carbon dioxide)
Downward displacement of air /
upward delivery
For gases which are less dense than air
(e.g. hydrogen, ammonia)
Upward displacement of air /
downward delivery
For gases which are denser than air
(e.g. chlorine, carbon dioxide, sulphur dioxide)
Using a gas syringe (for any gas) For any gas
26. Chapter 22: Non-metals
Moderately active metals, such as zinc, are used to react with mineral
acids to produce hydrogen gas.
The liberated hydrogen gas
is then bubbled through a
solution of concentrated
sulphuric acid.
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
Concentrated sulphuric acid
acts as a drying agent as it
removes any water
molecules present in the gas.
27. Chapter 22: Non-metals
Chlorine can be prepared by
removing hydrogen from
hydrochloric acid using an
oxidising agent, e.g.,
manganese dioxide.
Concentrated hydrochloric
acid is added to manganese
dioxide and the mixture is
heated.
MnO2(s) + 4HCl(l) → MnCl2(aq) + 2H2O(l)
+ Cl2(g)
Since chlorine is denser than air, it is
collected using downward delivery.
28. Chapter 22: Non-metals
When hydrogen peroxide is added to manganese dioxide, it
decomposes at room temperature, liberating oxygen gas.
2H2O2(l)→ 2H2O(l) +O2(g)
This method of collecting
oxygen is known as
downward displacement of
water.
29. Chapter 22: Non-metals
Carbon dioxide is normally produced by the action of dilute
hydrochloric acid on marble chips.
CaCO3(s) + 2HCl(aq) → CaCl2(aq) +H2O(l) + CO2(g)
The gas can be collected by the downward delivery method.
30. Chapter 22: Non-metals
Sulphur dioxide can be prepared by treating sodium sulphite with
dilute sulphuric acid or hydrochloric acid.
Na2SO3(s) + 2HCl(aq) → 2NaCl (aq) +H2O(l) + SO2(g)
The SO2 produced is passed
through a gas washing bottle
containing concentrated
sulphuric acid. The gas is
dried and collected by
downward delivery.
31. Chapter 22: Non-metals
Ammonia can be prepared by heating an ammonium salt with a strong
base. In the lab, ammonia is prepared by heating a mixture of solid
ammonium chloride and calcium hydroxide.
2NH4Cl(s) + Ca(OH)2(aq) → CaCl2(s) +2H2O(l) + 2NH3(g)
Ammonia gas is
collected by upward
delivery as it is less
dense than air. Since
water is also
produced, the gas is
dried by passing
through a drying
tower filled with a
drying agent.
32. Chapter 22: Non-metals
CH4(g) + H2O(g) → CO(g) + 3H2(g)
Steam is mixed with methane (the main constituent of natural gas),
with a nickel catalyst at a temperature of 1200 °C and 50 atm
pressure to produce hydrogen gas.
33. Chapter 22: Non-metals
• Chlorine is produced by the electrolysis of a concentrated aqueous
solution of sodium chloride known as brine.
• The anode is made of graphite (or titanium) while the cathode is made
of mercury.
• Chloride ions migrate to the anode and are discharged.
• Sodium ions are preferentially discharged to form sodium.
• Sodium combines with the mercury cathode to form sodium amalgam.
• The amalgam is treated with water to produce sodium hydroxide and
hydrogen gas. The mercury is thus freed up for use as cathode again.
• Since chlorine reacts with sodium hydroxide, they must be produced
in separate chambers and kept apart. This is achieved by the use of a
circulating mercury cathode.
The mercury cell process
At the anode: 2Cl-
(aq) – 2e-
Cl2 (g)
At the cathode: Na+
(aq) + e-
Na (l)
Chlorine
formed
34. Chapter 22: Non-metals
• The anode and cathode are separated by an ion-
exchange membrane.
• The membrane allows sodium ions and water to
pass through, but not chloride ions.
The membrane cell process
At the anode: 2Cl-
(aq) – 2e-
Cl2 (g)
At the cathode: 2H+
(aq) + 2e-
H2 (g)
Chlorine
formed
35. Chapter 22: Non-metals
• Most of the sulphuric acid in the world today is
manufactured by the Contact Process.
• The Contact Process involves the catalytic
oxidation of sulphur dioxide, SO2, to sulphur
trioxide, SO3.
The Contact Process
36. Chapter 22: Non-metals
Sulphur dioxide
(from burning of sulphur or
roasting of iron sulphide)
Sulphur dioxide
(from burning of sulphur or
roasting of iron sulphide)
Sulphur dioxide
+
Excess Air
Sulphur dioxide
+
Excess Air
450 o
C
1 – 2 atm
Vanadium(V) oxide
catalyst
450 o
C
1 – 2 atm
Vanadium(V) oxide
catalyst
Sulphur trioxide
dissolved in conc. sulphuric
acid
Sulphur trioxide
dissolved in conc. sulphuric
acid
OleumOleumSulphuric acidSulphuric acid
Water
unreacted
sulphur dioxide
unreacted
sulphur dioxide
37. Chapter 22: Non-metals
Step 1: Conversion of Sulphur to Sulphur Dioxide
Sulphur dioxide is obtained from the burning of sulphur.
Most of the sulphur is obtained as a by-product of petroleum
refining. Sulphur burns in air to form a colourless pungent
gas called sulphur dioxide:
S(s) + O2(g) SO2(g)
In some factories, sulphur dioxide is obtained as a by-
product from the roasting of iron pyrites in the extraction of
iron.
4FeS2(s) + 11O2 2Fe2O3(s) + 8SO2(g)
38. Chapter 22: Non-metals
Step2: Conversion of Sulphur Dioxide to Sulphur Trioxide
The sulphur dioxide is mixed with excess air and passed through a
filter to remove impurities and particles before entering the reaction
chamber.
The reaction chamber (converter) contains finely divided vanadium(V)
oxide as a catalyst at a temperature of about 450 °C – 500 °C. The
conversion of sulphur dioxide to sulphur trioxide occurs.
2SO3
(g) ∆H = -189 kJmol-1
The heat evolved in the exothermic reaction maintains the
temperature of the catalyst. By using several converters in series and a
slight excess of oxygen, about 98% conversion of sulphur dioxide into
sulphur trioxide is achieved.
2SO2
(g) + O2
(g)
39. Chapter 22: Non-metals
Step 3: Conversion of Sulphur Trioxide into Oleum
The sulphur trioxide is dissolved in concentrated sulphuric acid to form
a fuming liquid called oleum:
SO3(g) + H2SO4(l) H2S2O7(l)
Sulphur trioxide is not dissolved directly in water because the reaction is
extremely vigorous and will result in the production of a mist of fine
sulphuric acid particles which is damaging to health.
Step 4: Conversion of Oleum to Sulphuric Acid
The oleum obtained is carefully diluted with the correct amount of water
to form concentrated sulphuric acid:
H2S2O7(l) + H2O(l) 2H2SO4(l)
40. Chapter 22: Non-metals
Optimal Conditions for the Conversion
of Sulphur Dioxide to Sulphur Trioxide
The oxidation of sulphur dioxide to sulphur trioxide is a reversible
reaction, and is therefore affected by the experimental
conditions.
2SO2(g) + O2(g) 2SO3
(g) ∆H = -189 kJmol-1
- As it is an exothermic reaction, lower temperatures would
favour the production of more sulphur trioxide and result in a
higher yield. A temperature of 450 °C is favourable.
- Higher pressure would favour the yield of the product.
However, extreme high pressure is not necessary as the yield is
already very high (98%) at a pressure of 1 – 2 atm.
- A vanadium catalyst, vanadium(V) oxide, is also used in this
reaction to speed up the rate of the reaction.
41. Chapter 22: Non-metals
The Haber Process
• The process for manufacturing ammonia from
nitrogen is called the Haber Process, named
after its inventor, Fritz Haber.
The Haber Process
450 – 500 o
C
42. Chapter 22: Non-metals
• Hydrogen is obtained by the action of steam on natural
gas or from the cracking of petroleum fractions.
• A mixture of three parts by volume of hydrogen to one
part of nitrogen is compressed to a pressure of about
200 atm and passed over an iron catalyst heated to a
temperature of about 450 o
C.
• A yield of 17% – 20 % of ammonia is formed because the
reaction is reversible.
• Under these conditions, the nitrogen reacts with the
hydrogen to form ammonia according to the equation:
2N2
(g) + 3H2
(g) 2NH3
(g) ∆H = -92.4 kJ mol-1
43. Chapter 22: Non-metals
World’s Production of Ammonia
• The annual production of ammonia has been increasing rapidly
since the end of World War II (Fig 24.6).
• 140 million tonnes of ammonia are produced per year.
• Most of the ammonia is used in the manufacturing of fertilisers.
• The use of fertilisers has increased the yield of food crops
which in turn supports a continuing rise in world population.
Fig 22.5 World production of ammonia is rising rapidly
44. Chapter 22: Non-metals
Uses of Ammonia
• The ammonia manufactured in the Haber process is
used in the industry for many purposes.
• Large quantities of ammonia are used in the
manufacture of fertilisers like ammonium nitrate,
ammonium sulphate and urea.
• Ammonia is also used in making nitric acid. This is
done by the catalytic oxidation of ammonia into
nitrogen oxide which is then made into nitric acid. Nitric
acid can be used for making explosives and textiles.
• Ammonia solution is commonly used as a cleaning
agent for dry cleaning and making window cleaners.
Ammonium fertiliser Nitric acid Window cleaner
45. Chapter 22: Non-metals
• The most important use is for making sulphuric acid.
• It is used for bleaching wool and silk as it is a mild
reducing agent and would not damage the material.
• It is used for bleaching wood pulp for paper-making.
• It is used as a preservative for wine and other foodstuff
such as jams, tomato sauces and dried fruits. Sulphur
dioxide kills bacteria in the food and helps to maintain
the appearance of the foodstuff.
Uses of Sulphur Dioxide
46. Chapter 22: Non-metals
Preparations and collectives
of Non-metals
Chapter 22
Quick Check 2
1. Why are some gases prepared in the laboratory passed
through concentrated sulphuric acid?
2. Why is quick lime (calcium oxide) used to dry
ammonia instead of concentrated sulphuric acid?
Solution
47. Chapter 22: Non-metals
Solution to Quick Check 2
1. To remove water vapour from the gas
2. Because alkaline ammonia reacts with sulphuric acid
to form ammonium sulphate.
2NH3 + H2SO4 → (NH4)2SO4
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