Hoa dai cuong_chuong 8

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General Chemistry: Chapter 8
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Chapter 8: The Atmospheric Gases and Hydrogen
Philip Dutton
University of Windsor, Canada

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General Chemistry
Principles and Modern Applications
Petrucci • Harwood • Herring
8th Edition
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General Chemistry: Chapter 8
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Contents
8-1 The Atmosphere
8-3 Nitrogen
8-4 Oxygen
8-5 The Noble Gases
8-6 Hydrogen
Focus on The Carbon Cycle



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8-1 The Atmosophere
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Composition of Dry Air
trace
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Water Vapor
nH2O  PH2O in air.
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Chemicals from the Atmosphere
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8-2 Nitrogen
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Haber Bosch Process
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Anhydrous Ammonia as Fertilizer
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Nitrogen Oxides
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Nitric Acid Production
Oxidizing acid.
Nitration of organic compounds.
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Nitroglycerine
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Smog
Sunlight plus products of combustion – photochemical smog.
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8-3 Oxygen
Most abundant of elements in Earths crust.
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Electrolysis
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Ozone
O3 is an allotrope of oxygen.
An excellent oxidizing agent.
3 O2(g) → 2 O3(g) H° = +285 kJ
O2 + UV radiation → 2 O
M + O2 + O → O3 + M*
O3 + UV radiation → O2 + O
O3 + O → 2 O2 H° = -389.8 kJ
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Ozone Depletion
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Ozone Depletion
O3 + NO → NO2 + O2
NO2 + O → NO + O2
O3 + O → 2 O2
Natural:
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8-4 The Noble Gases
In 1785 Cavendish could not get all the material in air to react in an electric discharge.
100 years later Rayleigh and Ramsay isolated argon.
Greek argos—the lazy one.
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Noble Gases
Used in light bulbs, lasers and flash bulbs.
He and Ar are used as “blanket” materials to keep air out of certain systems.
He is used as a breathing mixture for deep diving applications.
Superconducting magnets use He(l) as coolant.

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Helium
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8-5 Oxides of Carbon
370 ppm CO2 in air. CO only minor.

Rich combustion:


Lean combustion:
C8H18(l) + 12.5 O2 → 8CO2(g) + 9 H2O(l)
C8H18(l) + 12 O2 → 7CO2(g) + CO(g) + 9 H2O(l)
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Hemoglobin
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Industrial Preparation of CO2
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Greenhouse Effect
Incoming sunlight hits the earths surface.
Earths surface emits infrared light.
IR absorbed in atmosphere by CO2 and other greenhouse gases. Atmosphere warms up.
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Global Warming
Predict 1.5 to 4.5°C average global temperature increase.
Computer models.
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8-6 Hydrogen
Minor component of atmosphere.
90% of atoms and 75% of universe mass.
Produced using the water—gas reactions:
C(s) + H2O(g) → CO(g) + H2(g)
CO(g) + H2O(g) → CO2(g) + H2(g)
Or by the reforming of methane:
CH4(g) + H2O(g) → CO(g) + 3 H2(g)
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Compounds of Hydrogen
Covalent hydrides
HCl, NH3
Ionic Hydrides
CaH2, NaH
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Uses of Hydrogen
Hydrogenation reactions
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Uses of Hydrogen
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Focus on The Carbon Cycle
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Chapter 8 Questions
1, 2, 5, 9, 10, 23, 29, 35, 41, 45, 53, 60, 63.