Hydrogen, Oxygen and Water

1
Hydrogen, Oxygen and Water

• Chapter 18

2
Hydrogen Chemistry

• Hydrogen Greek- hydro-water and genes-forming
• 11.0079H
• The lightest element and has only proton and one
  electron and it has no neutron.
• All other elements were originally made from
  hydrogen atoms or other elements that were
  originally made from hydrogen atoms.

3
Hydrogen History

• 1671 - Robert Boyle dissolved iron fillings in
  dilute hydrochloric acid and reported that the
  fumes given off were highly flammable.
• 1766 - Discovered and isolated by Henry Cavendish
  in 1766. 1781-H2O2 ED ? H2O
• 1781 Named Hydrogen by Antoine Lavoisier.
• 1789- van Troostwijk Deiman-Electrolysis of
  water-
• 1898 - James Dewar produced the first liquid
  hydrogen.
• 1900 - the first Zeppelin Airship made its
  flight filled with hydrogen.
• 1909-The pH scale by P. L. Sørensen
• 1923-J. N. Brønsted defined an acid as a proton
  donor.
• 1931 - Harold Urey discovered deuterium.
• 1947-LiAlH4 prepared by H. I. Schlesinger-Chicago
  University
• 1954-Detonation of H-Bomb on Bikini Atoll
• 1960s Super acid (BF3-HF)G. A. Olah.. Nobel 1994
• 1978- H. C. Brown Nobel Prize, Purdue University,
  Hydroboration
• 1984-First Stable T.M. dihydrogen compound
  discoved by G. Kubas
• 1996 - Metallic hydrogen was prepared

Hindenburg 1937
H-Bomb 1952
1900-1930s German war machine
1891 water splitting Poul la Cour -Danish
4
Why Hydrogen?
Hydrogen is a Part of Life
H2O , NH3, MeOH .
The first hydrogen refueling station Reykjavík,
Iceland in April 2003. DaimlerChrysler fuel cell
buses went into public use in nine cities
across the European Union in 2004.
Hydrogen Economy
5
Some Uses Hydrogen

• Selected uses of hydrogen
• Food ... to hydrogenate liquid oils (e.g.
  soybean, fish, cottonseed and corn) converting
  them to semisolid materials such as shortenings,
  margarine and peanut butter.
• Chemical processing ... primarily to manufacture
  ammonia (nitrogen fixation), hydrochloric acid
  and methanol, but also to hydrogenate non-edible
  oils for soaps, insulation, plastics, ointments
  and other specialty chemicals.
• Metal production and fabrication ... to serve as
  a protective atmosphere in high-temperature
  operations such as stainless steel manufacturing
  commonly mixed with argon for welding austenitic
  stainless. Also used to support plasma welding
  and cutting operations.
• Pharmaceuticals ... to produce sorbitol (sugar
  alcohol) used in cosmetics, adhesives,
  surfactants, and vitamins A and C.
• Aerospace ... to fuel spacecraft, but also to
  power life-support systems and computers,
  yielding drinkable water as a by-product.
• Electronics ... to create specially controlled
  atmospheres in the production of semiconductor
  circuits.
• Petroleum Recovery and Refinery ... to enhance
  performance of petroleum products by removing
  organic sulfur from crude oil, as well as to
  convert heavy crude to lighter, easier to refine,
  and more marketable products. Hydrogen's use in
  reformulated gas products helps refiners meet
  Clean Air Act requirements.
• Power Generation ... to serve as a heat transfer
  medium for cooling high speed turbine generators.
  Also used to react with oxygen in the cooling
  water system of boiling water nuclear reactors to
  suppress stress corrosion cracking in the cooling
  system.
• Fuel Cells ... used as a fuel to power fuel cell
  generators that create electricity through an
  electrochemical process in combination with
  oxygen.

6
Occurrence

• Hydrogen (hydrogen atoms) is the most abundant
  element in the universe (90 of all atoms and ¾
  of total mass), followed by Helium.
• Hydrogen is found in the stars and plays an
  important role in powering the Universe through
  interstellar proton-proton reaction and
  carbon-nitrogen cycle.
• 41H?4He 2e 2ne Q 26.72 MeV _at_ T
  gt 107K
• QEnergy evolved
• (?e is neutrino)
• 41H 12C?4He 12C 2e 2ne Q 26.72 MeV
  _at_ T gt1.6x107
• Hydrogen is the third (after oxygen and silicon)
  most abundant element in earth.
• Despite its simplicity and abundance, hydrogen
  doesn't occur naturally as a gas on the
  Earthit's always combined with other elements.

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Hydrogen

• 11.0079H Nuclear spin ½
• Electron Spin ½
• Electronic configuration
• 1s1 (H.)
• 1s1 - e- ? 1s0 (H)
• 1s1 e- ? 1s2 (H-)

8
Location in the Periodic Table
1 2 2 17 18
11.008H 1s1 ? ? 11.008H 1s1 2He 1s2
3Li .2s1 4Be 9F 2s22p7 10Ne 2s2sp6
11Na.3s1 12Mg 17Cl
19K. 4s1 20Ca 35Br
37Rb 5s1 38Sr 53I
55Cs 6s1 56Ba 85At
87Fr 7s1 88Ra
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Summary

• Despite its position on top of Group I, it is not
  really part of this group
• It is a gas and not a metal.
• It does not react with water.
• Far more electronegative than the alkali
• Electronegativity is the tendency of an atom in a
  molecule to attract electrons.
• Electronegativity is useful in predicting the
  general chemical behavior of an element.
• In general large difference in electronegativity
  between two elements leads to the formation of
  ions and small difference in electronegativity
  leads to sharing of electrons.

Selected Electronegativities (Pauling Scale) Selected Electronegativities (Pauling Scale)
F 4.0
Cl 3.0
O 3.5
N 3.0
S 2.5
C 2.5
H 2.1
B 2.0
Na 0.9
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Nuclear Properties Hydorgen Isotopes Nuclear Properties Hydorgen Isotopes Nuclear Properties Hydorgen Isotopes Nuclear Properties Hydorgen Isotopes Nuclear Properties Hydorgen Isotopes Nuclear Properties Hydorgen Isotopes
Isotope Symbol Natural Abundance, ½-life Nuclear Spin NMR Sensitivity
Protium 1H 99.985 Stable ½ 1.000
Deuterium, 12H, D 0.01 Stable 1 0.0097
Tritium 13H, T 10-17 Radio-active b-emitter 12.4 year 1/2 1.21
Have the largest isotope effect of all elements because of the largest mass differences. The dominant isotope. Natural hydrogen contains 0.002 D. b-radiation ? 0-1e Have the largest isotope effect of all elements because of the largest mass differences. The dominant isotope. Natural hydrogen contains 0.002 D. b-radiation ? 0-1e Have the largest isotope effect of all elements because of the largest mass differences. The dominant isotope. Natural hydrogen contains 0.002 D. b-radiation ? 0-1e Have the largest isotope effect of all elements because of the largest mass differences. The dominant isotope. Natural hydrogen contains 0.002 D. b-radiation ? 0-1e Have the largest isotope effect of all elements because of the largest mass differences. The dominant isotope. Natural hydrogen contains 0.002 D. b-radiation ? 0-1e Have the largest isotope effect of all elements because of the largest mass differences. The dominant isotope. Natural hydrogen contains 0.002 D. b-radiation ? 0-1e
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Isotope Effects Hydorgen Isotopes Isotope Effects Hydorgen Isotopes Isotope Effects Hydorgen Isotopes Isotope Effects Hydorgen Isotopes Isotope Effects Hydorgen Isotopes Isotope Effects Hydorgen Isotopes
Isotope H2 D2 H2O D2O
Boiling point/oC -252.81 -249.7 100.00 101.42
Mean Bond Enthalpy (kJmol-1) 436.0 443.3 463.5 470.9

See Deuterium and Tritium Isotopes synthesis and applications. Major used in spectroscopy as tracers to confirm the presence or absence of certain isotopes. See Deuterium and Tritium Isotopes synthesis and applications. Major used in spectroscopy as tracers to confirm the presence or absence of certain isotopes. See Deuterium and Tritium Isotopes synthesis and applications. Major used in spectroscopy as tracers to confirm the presence or absence of certain isotopes. See Deuterium and Tritium Isotopes synthesis and applications. Major used in spectroscopy as tracers to confirm the presence or absence of certain isotopes. See Deuterium and Tritium Isotopes synthesis and applications. Major used in spectroscopy as tracers to confirm the presence or absence of certain isotopes. See Deuterium and Tritium Isotopes synthesis and applications. Major used in spectroscopy as tracers to confirm the presence or absence of certain isotopes.
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Preparation of Hydrogen

• Reaction of electropositive metals with water
• e.g.
• 2 Na 2 H2O ? H2 2 Na 2 OH-
• Ca 2 H2O? H2 Ca2 2 OH-
• In the lab reaction of Fe or Zn with acids
• Zn 2 H3O ? H2 Zn2 2 H2O

13
Preparation of Hydrogen

• Electrolysis-
• 2H2O (l) es ? 2H2(g) O2(g) on
  inert electrode, e.g. Pt electrode
• Write balance half-reactions for the electrolysis
  of water?
• Show balanced half-reactions for the electrolysis
  of water.
• 2NaCl(l) 2Hg es ? 2NaHg(l) Cl2(g)
• 2NaHg (l) H2O(l) ? 2H2(g) 2Hg(l)

14
Reactions of Molecular Hydrogen (H2)

• Reaction with O2
• H2(g) O2(g) ? N.R
• 2H2(g) O2(g) ED ? 2H2O(l)
• Reaction with H2O
• H2(g) H2O(l) ? N.R.
• Reaction with Halogens
• H2(g) F2(g) ? 2HF(g)
• Reaction with acids
• H2(g) H(l) ? N.R.
• Reaction with bases
• H2(g) OH-(l) ? N.R.

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Hydrides

• Ionic (saltlike) hydrides
• when hydrogen combines with very active metals
  from Group I or Group II
• the hydride ion (H-) is a strong reducing agent
• ionic hydrides react violently in water
• LiH H2O --gt H2 Li OH-
• Covalent hydrides
• when hydrogen combines with other nonmetals, e.g.
  in HCl, NH3, CH4, and H2O

16
Hydrides

• Metallic hydrides
• formed when transition metal crystals are treated
  with hydrogen gas
• the hydrogen atoms migrate into the crystal
  structure to occupy holes or interstices
• a solid solution is formed
• when these interstitial hydrides are heated, H2
  gas is released
• use these intersitial hydrides for hydrogen gas
  storage

17
Covalent Hydrides

• The electrons in the bond are shared between M
  H.
• The electronegativity of the element 2.1 and
  varies from 2.5-1.5.
• Bond polarity depends on electronegativity
  differences between M H and varies from d (e.g.
  S-H) to d- (e.g. B-H and Ga-H)

Electronegativity Electronegativity
H 2.1
P 2.2
S 2.5
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Hydrides
1 2 13 14 15 16 17
LiH BeH2 (BH3)2, . CH4 NH3 H2O HF
NaH MgH2 (AlH3)n SnH4 PH3 H2S HCl
KH CaH2 GaH3 GeH4 AsH3 H2Se HBr
RbH SrH2 InH3 SnH4 SbH3 H2Te HI
Ionic Hydrides EH- Ionic EdHd- Covalent E-H Covalent HdEd-
Red Blue White
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Selected hydrides of p-block elements that contain M-H covalent Bonds, Selected hydrides of p-block elements that contain M-H covalent Bonds, Selected hydrides of p-block elements that contain M-H covalent Bonds, Selected hydrides of p-block elements that contain M-H covalent Bonds, Selected hydrides of p-block elements that contain M-H covalent Bonds,
13 14 15 16 17
B2H6 CnH2n2 NH3 H2O HF
CnH2n
CnH2n-2
(AlH3)n SinH2n2 (n ? 8) PH3 H2S HCl
P2H4 H2Sn
GenH2n2 (n ? 9) AsH3 H2Se HBr
SnH4 SbH3 H2Te HI
Polarity varies depending on electronegativity differences of M-H bond. Group 13 hydrides are electron deficient- Polarity varies depending on electronegativity differences of M-H bond. Group 13 hydrides are electron deficient- Polarity varies depending on electronegativity differences of M-H bond. Group 13 hydrides are electron deficient- Polarity varies depending on electronegativity differences of M-H bond. Group 13 hydrides are electron deficient-

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Reaction of Ionic Hydrides with water
21
Oxygen Chemistry

• Oxygen Greek-oxus or oxys (sharp, acid) and
  geinomai or genes (former)-acid former
• 815.9994O 1s22s22p4
• The most abundant element in the universe and has
  eight proton, eight electron and eight neutron.
• Oxygen is an important component of air, produced
  by plants during photosynthesis and is necessary
  for aerobic respiration in animals.

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History

• lt1771- prepared by many individuals but were not
  able to isolate it or recognize it as an element.
• In 1770, G.E. Stahl, a German physician - all
  inflammable objects contained a material
  substance that he called "phlogiston," from a
  Greek word meaning "to set on fire."
• 1771 Carl Wilhelm Scheele (Swedish pharmacist)
  discovered Oxygen called it fire air was not
  immediately recognized.
• 1772 - Joseph Black (Scottish chemist), and his
  student, Daniel Rutherford- a living creature
  gives up phlogiston while breathing and when
  placed in air that is already saturated with
  phlogiston, can no longer breathe and must die.
• 1774 Joseph Priestley independent discovery
  confirmed oxygen.
• 1774 Antoine Laurent Lavoisier oxygen.
• 1848 - Faraday while he was investigating the
  magnetic susceptibility of matter, he discovered
  that oxygen could be drawn into a magnetic field
  (paramagnetic).
• 1950 - Paul Hersch developed electrochemical
  oxygen sensor. 
• Scheele Joseph Priestley Antoine L.
  Lavoisier Benjamin Franklin
  Cartoon of Priestley calling for the head
• Radical Thinker wife
  Marie-Ann Paulze
• (Through a conscious revolution, became the
  father of modern chemistry) of King George III.
• (Law degree at the Collège Mazarin)

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Why Oxygen?

• Oxygen is a part of life - supports all life on
  this planet and is essential to combustion as
  well as respiration
• Photosynthesis Respiration Agriculture Environmen
  t
• Chemicals, H2O2 Zeolites

Electronegativity
Electronegativity
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Oxides

• Binary Oxygen compounds are generally referred
  to as
• oxides
• With metals the compounds may be
• (a) oxides O2- - oxidation number (2)
• (b) peroxides O22- - oxidation number (1)
• (c) superoxides O2- - oxidation number (- ½ )
• Oxides may be acidic, basic, neutral or
  Amphoteric

25
Selected Uses of Oxygen

• Essential for many important industrial and
  biological processes that may include
• Oxidizer (only fluorine having a higher
  electronegativity) used in rocket propulsion and
  manufacturing disinfectant, pharmaceuticals,
  etc.
• Medicine Biological life support- Respiration -
  oxygen supplementation, gas poisoning, and
  anesthetic when mixed with nitrous oxide, ether
  vapor, etc..
• Oxygen is essential for life takes part in
  processes of combustion respiration.
• Oxygen is used in welding.
• Metalloragy- melting, mining, refining and
  manufacture of steel, other metals and
  manufacture of stone and glass products.
• Recreational - mild euphoric, has a history of
  recreational use often mixed with nitrous oxide
  to promote a kind of analgesic effect.
• Manufacture of chemicals by controlled oxidation

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Occurrence

• Oxygen is the most abundant element in the
  Universe originated by green-plant
  photosynthesis.
• chlorophyl/enzyme
• H2O CO2 hv ? O2 CH2O DH /-
  469 kJmol-1
• Oxygen comprises about 46.7 of earths crust,
  87 by weight of the oceans (as H2O) and 20 of
  the atmosphere of Earth (as O2, molecular oxygen,
  or O3, ozone).
• Oxygen compounds, particularly metal oxides,
  silicates (SiO44-), and carbonates (CO32-), are
  commonly found in rocks and soil.
• Frozen water is a common solid on the outer
  planets and comets. The ice caps of Mars are made
  of frozen carbon dioxide.
• Oxygen compounds are found throughout the
  universe and the spectrum of oxygen is often seen
  in stars (see carbon-nitrogen-oxygen cycle in
  1H-1H fusion.

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Forms of oxygen

• Molecular O2, O3 and O4 (allotropes)
• Atomic- highly reactive
• Ionic- oxides O2-, peroxides O22-, superoxides
  O2-, . (see group I and II oxides).
• Molecular (covalent) compound of oxygen neutral
  (e.g. SiO2, OsO4, CO2..) ionic (e.g. SO42-,
  CO32-, NO3-, )

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Molecular oxygen

• Oxygen is a colorless, odorless gas and at
  standard pressure, oxygen liquefies to a pale
  blue liquid which boils at -183.0 ºC. Solid
  oxygen melts at -218.8 ºC. Oxygen is sparingly
  soluble in water slightly heavier than air.
• Liquid O2

29
Chemical Synthesis of O2

• From water
• Electrolysis (see synthesis of hydrogen).
• Chemical oxidation of water
• 2H2O 2Cl2 ? 4HCl O2
• From oxides
• Thermal decomposition
• e.g. 2HgO ? 2Hg O2
• 2BaO2 ? 2 BaO O2
• 2KMnO4 ? K2MnO4 MnO2 O2
• chemical decomposition
• e.g. MnO2 2H2SO4 ? 2MnSO4 2H2O O2
• Catalytic decomposition of peroxides

30
Industrial Production

• Fractional distillation of liquefied air _at_-183 C
  (O2) and _at_ -196 C .

Air
Gas Volume
N2 78.1
O2 20.9
Ar 0.93
CO2 0.035
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O2 Haemoglobin

• Active site metalloprophyrin

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Di-oxygen metal compounds

• Metal-dioxygen compounds
• http//www.res.titech.ac.jp/smart/research/subjec
  t(e).html
• http//www.iuac.org/publications/pac/1995/pdf/670
  2x0241.pdf

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Main Group Oxides Ionic vs Covalent

• With the exception of a few Nobel gas elements
  such as Xe, oxygen forms oxides with all elements
  in the periodic table.
• If D Electronegativity gt 1.5
• the oxide is ionic.
• If D Electronegativity lt 1.5
• the oxide is covalent.

Selected Electronegativities (Pauling Scale) Selected Electronegativities (Pauling Scale)
F 4.0
Cl 3.0
O 3.5
N 3.0
S 2.5
C 2.5
H 2.1
B 2.0
Na 0.9
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Main Group Oxides
Increasing covalent acidic character
1 2 13 14 15 16 17
Li2O BeO B2O3 CO2 N2O5
Na2O MgO Al2O3 SiO2 P4O10 SO3 Cl2O7
K2O CaO Ga2O3 GeO2 As2O5 SeO3 Br2O5
Rb2O SrO In2O3 SnO2 Sb2O5 TeO3 I2O5
Cs2O BaO2 Th2O3 PbO2 Bi2O5
Ionic Basic Amphtoeric Covalent Acidic
Red Blue White
Increasing ionic basic character
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Hydrolysis of goup I II oxides

• M2O H2O ? 2M 2OH- oxides (O2-)
• M2O2 2H2O ? 2M 2OH- H2O2
• peroxide (O22-)
• 2MO2 2H2O ? O2 2M 2OH- H2O2
• superoxide (O2-1)
• M Group I metal in this case

37
Reaction of Oxides and Superoxides with water
38
Hydrogen Peroxides

• Why Hydrogen Peroxide?

39
Selected Uses of Hydrogen Peroxides

• Multipurpose Disinfectant - Kills mold, mildew,
  fungi, viruses, bacteria and other harmful
  biological contaminants.
• Health toothpaste, mouthwash, shower, facial
• Agriculture - Sprouting Seeds, House and Garden
  Plants, Vegetable Soak
• Powerful Oxidizer for a variety of organic and
  inorganic compounds 
• "green" bleaching agents for the paper and
  textile industries.
• Wastewater treatment.
• Hydrometallurgical processes (for example, the
  extraction of uranium by oxidation)
• Bleaching agent - paper, textile, teeth and hair

40
Synthesis of Hydrogen Peroxides

• Hydrolysis of Group I and II peroxides
• e.g. BaO2 2H2O ? H2O2 Ba(OH)2
• Nature photolysis acid-base conversion of O3
• O3 H2O ? H2O2 O2 hn
• O3 HO- ? HO2- O2 _at_ high pH
• HO2- H2O ? H2O2 HO-
• Electrolysis aqueous solutions of sulfuric
  acids, of potassium bisulfate, or of ammonium
  bisulfate
• 2HSO4-(aq) -2e- ? HSO3OOSO3H
• HSO3OOSO3H H2O ? 2HSO4- H2O2
• Describe the synthesis of D2O2.

41
Reactions of Hydrogen Peroxide

• H2O2 is metastable and decomposes as shown below
• 2H2O2 ? 2H2O O2 DH0 -98.2 kJmol-1
• DG0 -119.2 kJmol-1
• (Heterogeneous (e.g. MnO2, Ag, Au or Pt) and
  homogenous (e.g. OH-, I-, Cu2 or Fe3) enhance
  decomposition)
• H2O2 ? 2HO. (in cold, dark catalyzed at high
  T and hn)
• (HO. highly reactive . chain reactions )

42
Determing Formula of Hydrate,x.

1. Get mass of sample.
2. Heat sample up to release water.
3. Get mass again. This will be mass of anhdrous
   salt mass of water is found by subtraction.
4. From mass of water and anhdrous salt determine
   moles of each.

43
Determining Formula of Hydrate,x.

• Determine x in Empirical Formula Hydrate. (_CuSO4
  .xH2O)
• X moles H2O / moles CuSO4
• Mass H2O (mass H2O/ mass unknown hydrate)100