*M11-P1 Materials from the Earth6th International Junior Science Olympiad (IJSO)Dr. Yu-San Cheungyscheung@cuhk.edu.hkDepartment of ChemistryThe Chinese University of Hong Kong

*Naturally occurring substancesConsidered valuable in their relatively unmodified (natural) formsValues: depending on the amount available and the demandA commodity is generally considered a natural resource when the primary activities associated with it are extraction and purification, as opposed to creation.Examples of natural resources:Air, water, and soilBiological resources - plants and animals Raw materials (like minerals) Space and land Energy (like wind, geothermal(), tidal(), and solar energy)Natural Resources()http://en.wikipedia.org/wiki/Natural_resourceshttp://www.ecofriendlykids.co.uk/NaturalResourcesEarth.html

*They can restock (renew) themselves, be used indefinitely if they are not over-harvested.If consumed at a rate that exceeds their natural rate of replacement, the standing stock will diminish and eventually run out. Examples of living renewable resources: trees (forests and woodlands) and cropsfish and livestockExamples of non-living renewable resources: fresh waterfresh airFlow renewable resources (or simply flow resources):renewable, but needing no regeneration or re-growthe.g., wind, tidal, and solar energyRenewable Resources()http://en.wikipedia.org/wiki/Natural_resourceshttp://www.ecofriendlykids.co.uk/NaturalResourcesEarth.html

*A non-renewable resource is a natural resource that cannot be re-made, re-grown, or regenerated on a scale comparative to its consumption.

Fossil fuels, such as coal, petroleum, and natural gas are often considered non-renewable resources, as they do not naturally re-form at a rate that makes the way we use them sustainable. Non-renewable Resources ()http://en.wikipedia.org/wiki/Natural_resources

*Forests: timber (for building houses, boats, decks, and furniture; and making paper)

Mines: metal products, fossil fuels, salts, jewelry, gravel (for building roads and concrete)

Aquaculture(): fishes, shrimps, crabs, etc.

Natural Resources and Their Productshttp://www3.iptv.org/exploremore/land/issues/iss_natu/natural_resources.cfm

*Periodic Chart.pdf in http://www.mii.org/Minerals and Their Chemical ComponentsExercise:

Find out the major chemical content in various types of minerals

*Common Minerals and Their Useshttp://www.mii.org/commonminerals.htmlExercise:

Find out the uses of some common minerals.

*Cement & Concretehttp://www.wisegeek.com/what-is-the-difference-between-concrete-and-cement.htm

Cement:made from limestone, calcium, silicon, iron, and aluminum, plus lesser amounts of other ingredientsWhen water is added to cement, a chemical process occurs as it dries, allowing it to harden.

Concrete:cement + aggregates (e.g., sand, stone)Important and widely-used construction materialStrengthened by steel-rod skeletonAnnual production: about 6 billion tons (~1 ton each person on the Earth)Life: 50,000 years

Cement: Concrete:

*Recycling()http://en.wikipedia.org/wiki/RecyclingRecycling is the reprocessing of materials into new products.It can save energy and reduce air pollution.Exercise:

Find out the environmental effects of recycling.

*Recycling ()http://en.wikipedia.org/wiki/RecyclingAggregates and concreteCrushed and used as aggregates for new concreteBatteriesDifficulty: so many types of batteriesSome old types contain mercury and cadmiumLead-acid battery (mostly used in automobiles): containing leadBiodegradable wasteElectronics waste (recovering metals)Various types of metals (e.g., _________________________________)PaperGlassPlasticRubber TextilesTimber

*Metalshttp://en.wikipedia.org/wiki/MetalIn chemistry:A metal is an element that readily loses electrons to form positive ions (cations) and the cations are surrounded by a sea of electronsMost metals form ionic bonds with non-metals [but not always, e.g., in Pb(C2H5)4, there is PbCH2CH3 covalent bond]

Physical properties:Electrical conductingSome hard, some soft, some being liquid

*Alloys()

Alloy: a homogeneous mixture of two or more elements, at least one of the elements is a metal, the resulting mixture has metallic properties.

An alloy usually has properties (physical and chemical) different from those of its components.

ExampleThe major component of steel is iron and steel is stronger than iron.If chromium is added, we have stainless steel which can resist corrosion.

http://en.wikipedia.org/wiki/Alloy

*Examples of Alloyshttp://en.wikipedia.org/wiki/Carbon_steelhttp://en.wikipedia.org/wiki/Stainless_steelhttp://en.wikipedia.org/wiki/Brasshttp://en.wikipedia.org/wiki/Bronzeshttp://en.wikipedia.org/wiki/Rose_goldhttp://en.wikipedia.org/wiki/Solderhttp://en.wikipedia.org/wiki/List_of_alloysCarbon steel: iron + carbon (higher carbon content, stronger but more brittle)- Low carbon steel: ~0.05 0.3% carbon content- Ultra-high carbon steel : ~1 2% carbon contentStainless steel: steel + chromium (> 10%)Brass: copper + zinc (typically ~30 35%)

Bronze: copper + tin (typically 12%)

Rose gold: gold + copper: for jewelry24k: 100% gold (18k: 75% gold) (k = karat)

Solder: Conventional: Sn60/Pb40 (60% tin + 40% lead)Lead-free: e.g., SnAgCu (tin + silver + copper); different SnAgCu compositions: different melting points

*Energy ResourcesSolar energyWind energyWater-related:hydro power pumped-storagetidal power wave power Geothermal energyBiomass energyGarbage energyNuclear energyFossil fuelshttp://home.clara.net/darvill/altenerg/index.htm

*Generation of Electrical Energy()Electrical energy is easily transported (from power plants to individual customers)

Electrical energy is versatile

Majority of energy available from Nature: in the form of kinetic energy and heat energy

Kinetic energy electrical energy

Heat energy kinetic energy of steam kinetic energy of magnet/metal electrical energy

*Lenzs Law()Faradays Law() of InductionIn effect: Changing magnetic field electrical currenthttp://hyperphysics.phy-astr.gsu.edu /Hbase/electric/farlaw.htmlThat is, kinetic energy electrical energy

*Turbine()Flow of fluid (acting on blazes) rotation of shaft

Kinetic energy of fluid kinetic energy of shaft electrical energy http://en.wikipedia.org/wiki/Turbine

*Solar Energy() Energy from the SunThe Sun is a nuclear reactor, 150 million km away. Only a small fraction of light energy and heat energy (1 part in 1010) reaches the Earth, but it is a huge amount to the Earth.

Ultra-violet(UV) Visible Infra-red (IR)

Solar cell: light energy electrical energyWater-heating system: heat energy heat energy of waterSolar furnaces: heat energy heat energy of gas kinetic energy of gas electrical energyhttp://home.clara.net/darvill/altenerg/solar.htmlightAbsorbed and becoming heat energyIncreasing wavelength

*Exercise:

How is solar energy used for heating water in Hong Kong?

Example:

http://www.cuhk.edu.hk/greencampus/en/communication/sc_spring07.pdf

*Wind Energy()Energy from windAncient application: sailingUsed since Middle Ages: windmill

Electricity generation: wind turbine electricity(reverse of electric fan operation)

http://home.clara.net/darvill/altenerg/index.htmWindPropeller bladesGearbox & generator in housing which can be rotated to face the windTower

*Hydro Power()Energy from the flow of water: (potential energy of water kinetic energy of water ) Ancient application: corn grinding, sailing, warUsed nowadays to generate 20% of the worlds electricityhttp://home.clara.net/darvill/altenerg/index.htmReservoirDamTurbineGenerator

*Pumped Storage ReservoirsThey are not facilities or methods to generate electrical power. They are a way of storing energy so that it can be released quickly when needed.

Demand for electrical power changes throughout the day. When the demand is low, extra power not used is wasted.

A facility is needed which can store excess energy produced, and can release the stored energy immediately. Pumped storage reservoirs can do the job.http://home.clara.net/darvill/altenerg/index.htmTopReservoirTurbines & PumpsLower Reservoir

*Tidal Power()Tide: water movement, containing kinetic energyTwice a day8 sites in Britain, generating 20% of energy needed ~20 potential sites in the worldLargest one: northern France http://home.clara.net/darvill/altenerg/index.htmTide coming inTide going out

*Off-shore Stationhttp://www.swanturbines.co.uk/http://www.marineturbines.com/technical.htm

*Wave PowerWave: generated by wind on sea surfaceMethod: reverse of a swimming pool wave machine

http://home.clara.net/darvill/altenerg/wave.htmWater level going up and downAir flowing in and out

*Geothermal Energy()The centre of the Earth: ~6000 Chot enough to melt rockA few km down the surface: > 250 CUsed for thousands of years in some countries for cooking and heating

If hot enough to produce steam electricityIf not: heating

http://home.clara.net/darvill/altenerg/geothermal.htmCold water downPower stationHot water downHot region

*Biomass()Energy from organisms (usually plants)Example: burning of wood for heat and lightExtraction of fuel: ethanol by fermentation: corns / canes cane sugar ethanol Biodiesel: a fuel made from vegetable oil that runs in any unmodified diesel engine. Triglycerides ()(Esters of glycerol with long-chain fatty acids)

*Triglycerides Biodiesel

*Use of Biodiesel in automobilesRecipe: Biodiesel from New OilExample:1994 Dodge: 100,000 miles on 100% Rapeseed ()http://www.dancingrabbit.org/biodiesel/newoil.phpBiodiesel

*Burning garbage: generating heat energy, but serious pollution (e.g., dioxin)Bacterial action: generating landfill gas (mainly methane, CH4)Garbage Energy

*Basis of Nuclear Physics & Nuclear Power

*Testing your knowledge on: molecules, atoms, and subatomic particlesA molecule consists of two or more _____ of the same or different elements. Examples: ____________________________Atoms are the smallest particles of an element.Sub-atomic particles: particles that constitute atoms. _________________________________Which of these sub-atomic particles make up nuclei?

*Compare the sizes of:molecules, atoms, and nuclei.

Testing your knowledge on: molecules, atoms, and subatomic particlesIsotopes are atoms of the same _______ but having different numbers of ________ in their ________.Exercise (fill-in-the-blank):

*A nuclear species characterized by specific values of the atomic number (no. of protons) and the mass number (no. of protons and neutrons)Nuclides()

*Nuclei of some atoms, e.g., 40K, are unstable. They undergo spontaneous transformation into more stable atoms. The substance is called radioactive.

Such a transformation process is called radioactive decay. It is usually accompanied by emitting particles and energy collectively called radiation.Radioactive()Substances

*The phenomena of radioactivity was discovered in 1896. This radiation was later shown to be separable by electric (or magnetic) fields into three types: alpha (a), beta (b) and gamma (g) rays.Radioactivity()Radioactive material+Lead blockElectric plate (negative)Electric plate (positive)Luminescent screen ray ray ray

* Unstable nuclei are radioactive

Nuclei consist of proton(s) & neutron(s) (except __________)

Forces inside the nuclei: (1) Repulsive Coulomb force: between protons (2) Attractive nuclear force: between proton & proton, neutron & neutron, proton & neutron

Stability depends on the balance of the two forcesStability of Nuclides()

* Alpha particle (helium-4 nucleus, 4He2+)

Beta particle (electron)

Gamma ray / X-ray (electromagnetic radiation)

NeutronRadioactive Decay Products

* Ionization and atomic excitation causing molecular rearrangement or formation of free radicals

Alteration of molecules leads to malfunction of physiological processes which depend on the chemical structure

Examples: inhibition of cell division, denature of enzymes, mutation of genetic materialsInteraction of Radiation with Cells

* Half-life (t1/2): the time it takes for half of its original amount to decay1 1/8 1/16 .After n half-lives, 1/(2n) is left.For example, after 10 half-lives, 1/(210) = 1/1024 (about 0.1%) is left.Rate of Radioactive Decay

*Radionuclide81Kr38K73Se131I60Co137Cs14C129I235U40KHalf-life13 seconds7.6 min7.2 hr8 days5.3 yr30 yr5730 yr17 million yr703 million yr1260 million yrEach radionuclide has a characteristic t1/2Half-lives of Some Radionuclides

* cosmic rays terrestrial radiation (including radon) food & drinks (40K within body) medical instruments leakage/disposal radioactive fallout (weapon testing) consumer products, e.g., smoke detectors, glow in the dark watchesSources of RadiationNatural RadiationArtificial Radiation

*Nuclear Fuel()235U + n 139Ba + 94Kr + 3nCharacteristics: Bombarded by neutron Chain reaction: 1 neutron in, 3 neutrons out.

But not every neutron can hit an 235U nucleus.The reaction may eventually stop.http://home.att.net/~cat4a/nuclear_III.htm

*Enriched Nuclear Fuel()To make the chain reaction self-sustaining, we need to use:uranium enriched in 235Usuper critical mass of the fuel

Natural uranium: 238U (99.3%) & 235U (0.7%)Enriched: 2-3% in 235U (>85% for bomb)Methods: centrifugation, diffusion, and electromagnetic isotopic separation.

*Critical Mass()Critical mass: sphere of 600 kg for 15% 235U (~40 cm diameter)Higher 235U percentage: larger/smaller critical massNeutron reflector: larger/smaller critical masshttp://en.wikipedia.org/wiki/Image:Critical_mass.svg

*Nuclear Power Plant()http://science.howstuffworks.com/nuclear-power2.htm

*Other Nuclear FuelsPlutonium-239 & Uranium-233

*Nuclear Fusion()Heavy nuclei favor fission.Light nuclei favor fusion.

Examples of nuclear fusions:2H + 3H 4He + n 2H + 2H 3He + n2H + 2H 3H + phttp://en.wikipedia.org/wiki/Nuclear_fusion

*Human-made Nuclear FusionIn order for a nuclear fusion to occur, two nuclei must be brought close enough.But the repulsion between nuclei is huge. Nuclei must contain high enough energy.

Human-made nuclear fusion: through nuclear fission in nuclear bomb

*Nuclear Fusion() in Nuclear Power PlantNuclear fusion: more energy released than fission But once started, nuclear fusion is out of controlled and cannot be stopped.Nuclear fusion for power generation: to be developed.

Other advantages of fusions over fissions: less hazardous products source more available (natural abundance of 2H: 0.015%)

*Accidents of Nuclear Power Plants Three Mile Island, USA (1979) Chernobyl, Ukraine, in former USSR (1986)

Leakage of highly radioactive materials

On the whole, non-nuclear large-scale industrial accidents result in higher tolls.

*Nuclear Weapons & Nuclear Power PlantsA nuclear power plant does not aim to make nuclear weapons.But the materials can be used for nuclear weapons.

Concerns: 235U: needs extra work to enrich its percentage 329Pu: created in a uranium reactor, the percentage of which is high enough for nuclear weapons

In addition to making a nuclear bomb (which can really explode), the waste can also used for dirty bomb.More about nuclear proliferation: http://en.wikipedia.org/wiki/Nuclear_proliferation

*Advantages & DisadvantagesAdvantagesNo CO2 is emittedNo air is needed

DisadvantagesIn case of accident, the damage is serious Using and producing materials, which are the source for nuclear weaponsDisposal of nuclear waste: waste cannot be destroyed

*Industrial Revolution: increases in the use of fossil fuelsSteam engines (late 1700s): needed fuels

chemical energy (stored in _______) heat energy (of _______) kinetic energy (of _______) kinetic energy (of _______) to run machines, cars, etc.Fossil Fuels()

*What are fossil fuels?Plants, animals, and microorganisms (living millions of years ago) deathRemains buried and subjected to high temperatures and pressures in Earths crust

Primarily hydrocarbons, CxHy

Fossil fuel sometimes also includes non-biological source such as tar sand, which is known as mineral fuel.

*CoalPetroleum (oil)Natural gasTar sands and oil shaleMethane hydrateTypes of Fossil Fuels()

*Carbon Cyclehttp://en.wikipedia.org/wiki/Image:Carbon_cycle_diagram.jpgAtmosphere ( )Fossil Fuels & Cement Production ( )Vegetation ( )Soils ( )Marine Biota ( )Dissolved Organic Carbon ( )Surface Ocean ( )Deep Ocean ( )Sediments ( )Exercise: Find out the carbon distribution in the Nature from internet.

*Heat Energy UnitsBTU (British Thermal Units) = 1054 1060 J

Quad: quadrillion BTU = 1015 BTU

Total U.S. energy use: ~100 Quad in 2005

A barrel of oil (bbl): ~6 million BTU

100 Quads: 17 billion barrels of oil(1 bbl = 42 gallons)http://www.opm.state.ct.us/pdpd2/energy/flows94.htmhttp://en.wikipedia.org/wiki/British_thermal_unit

*Coals() Plant remains covered by water and mud Readily combustible Black or brownish black in color Mainly composing of carbon, with an assortment of other elements (e.g., sulfur)

Most abundant of all fossil fuels, the largest single source of fuel for the generation of electricity world-wide

One of the major sources of carbon dioxide emissionshttp://en.wikipedia.org/wiki/Coal

*Worldwide Coal ProductionExercise:

Find out the worldwide coal production, coal reserves, and major coal exporters.

*Processing of CoalOther than being burnt directly, coal can be further processed to obtain higher-quality fuel.

Liquefaction: coal liquid fuels e.g., gasoline or diesel

Gasification: C + steam + O2 synthesis gas (CO + H2)

Coking (~ 1000 oC): driving off volatile substances to form coke

*Petroleum()(Oil, Crude Oil)Compression and heating of ancient organisms

Buried at the ocean bottom, where O2 was insufficient to oxidize all the organic materials

*Oil Producing and Consuming CountriesExercise:

Find out the major oil producing and consuming countries around the world.

*Petroleum()Hydrocarbon, mostly alkane (saturated CxHy): C5H12 to C18H38

Shorter hydrocarbon: natural gasLonger hydrocarbon: paraffin wax

High energy density, easy transportability, relatively high abundance

Source of raw material for many chemical products

*http://en.wikipedia.org/wiki/Oil_refineryOil Refinery: Separating Components of Different Molecular WeightsVery detailed flowchart: http://en.wikipedia.org/wiki/Image:RefineryFlow.pngExercise:

Find out various oil refinery products and their usages.

*Cracking()Breaking down long carbon chains

By heating & with catalysts

e.g. CH3CH2CH2CH3 CH2=CH2 + CH3CH3

*Knocking of Gasoline()Gasoline is burnt to produce energy in a combustion engine (e.g., of a vehicle)

Some gasoline start to burn before they are ignited by sparks.

This premature ignition produces a knocking sound. So it is sometimes called knocking.

Consequences of knocking: power loss and engine wearing

http://en.wikipedia.org/wiki/Octane_rating

*Octane RatingDifferent gasoline have different anti-detonation

Octane rating: a measure of the anti-detonation (or auto-ignition resistance) of gasoline and other fuels used in spark-ignition internal combustion engines.

http://en.wikipedia.org/wiki/Octane_rating

*iso-octane: set at 100 n-heptane: set at 0

A mixture of iso-octane and n-heptane: x% (by volume) in iso-octane, octane rating: x.

Example: 84 liters of iso-octane + 16 liters of n-heptane84% (by volume) in iso-octane16% (by volume) in n-heptaneOctane Rating: 84

It is found that 1-pentene has the same knocking property as this mixture, so we say that the octane rating of 1-pentene is 84.Octane Rating

*Octane RatingOctane rating can be smaller than 0 and larger than 100.

e.g., n-octane: -10benzene: 101ethane: 108

Octane rating for gasoline for vehicles: 85-90.http://en.wikipedia.org/wiki/Image:09-03-06-Octane.jpg

*Anti-knocking AgentTetra-ethyl lead (TEL): Added to gasoline to increase octane ratingAbout 0.05% of TEL in gasolinePb(CH2CH3)4, mostly covalent in nature, not containing Pb4+ and CH2CH3

How it works:Knocking causes formation of radicals, e.g., CH3, from gasolineChain reaction: these radicals destroy other gasoline moleculesPb(CH2CH3)4 Pb(CH2CH3)3 + CH2CH3 (or Pb + 4 CH2CH3 ?)These radicals from TEL and remove radicals from gasolineSometime literatures say that Pb + O2 PbO2 and the PbO2 reacts with the radicals from gasoline

Other anti-knocking agents (also called octane enhancers):methanol & ethanol

*Problems of Leaded GasolineLead is toxic to humans

It poisons Rh and Pt catalysts in catalytic converters (which convert NOx and VOC emitted from pipes of vehicles into harmless substances)

Rh = rhodiumPt = platinumBoth are metals with catalytic property

*Natural Gas() Formation process: similar to that of petroleum

Components: (%)methane (CH4): 70 90 ethane (C2H6): 5 15 propane (C3H8), butane (C4H10): < 5

CO2, N2, helium, and hydrogen sulfide (H2S): balanceExercise:

Find out the major natural gas producing and consuming countries around the world.

*Tar SandAlso called oil sand (actually more appropriate)

A mixture of extremely heavy crude oil, sand or clay, and water.

Natural material, nothing to do with tar (man-made)

Worldwide sources:Canada, Venezuela, and USA.http://en.wikipedia.org/wiki/Tar_Sands

*Oil Shale() A fine-grained sedimentary rock containing significant traces of kerogen (a solid mixture of organic chemical compounds) that have not been buried for sufficient time to produce conventional fossil fuels.

When heated to a sufficiently high temperature a vapor is driven off which can be distilled to yield a petroleum-like shale oil, a form of non-conventional oil, and combustible shale gas.

Can be burnt directly as a low-grade fuel for power generation and heating.

Can be used as a raw material in the chemical and construction materials industries.

Reserve: mainly in North America

http://en.wikipedia.org/wiki/Oil_shale

*Methane Hydrate (Methane Ice)

Ice that contains a large amount of methane within its crystal structure

Total amount: 500-2500 billion tons of carbon(carbon for all fossil fuel reserves: 5000 billion tons)

Natural gas hydrates (NGH) vs. liquefied natural gas (LNG) in transportation:NGH: stable up to 20 CLNG: stable up to 162 CTherefore, there is some interest in converting natural gas into NGH rather than LNG for transportation. http://en.wikipedia.org/wiki/Methane_hydrates

*******************************2*****Control rods are often made of boron or cadmium, which absorbs neutrons readily. Remove the controlling rods part way starts the chain reaction. The reaction is stopped when the rods are pushed in all the way.*Control rods are often made of boron or cadmium, which absorbs neutrons readily. Remove the controlling rods part way starts the chain reaction. The reaction is stopped when the rods are pushed in all the way.*****India produced and tested a nuclear bomb using plutonium recovered from reprocessed reactor fuel.**********Straight-run gasoline consists of mainly straight-chain hydrocarbons and is of limited value as an automobile fuel. The reason is that straight-chain hydrocarbons cause a fuel to begin burning before it is ignited by the spark plug, which produces a knocking sound and leads to loss of engine power and eventual damage to engine.*Straight-run gasoline consists of mainly straight-chain hydrocarbons and is of limited value as an automobile fuel. The reason is that straight-chain hydrocarbons cause a fuel to begin burning before it is ignited by the spark plug, which produces a knocking sound and leads to loss of engine power and eventual damage to engine.*Straight-run gasoline consists of mainly straight-chain hydrocarbons and is of limited value as an automobile fuel. The reason is that straight-chain hydrocarbons cause a fuel to begin burning before it is ignited by the spark plug, which produces a knocking sound and leads to loss of engine power and eventual damage to engine.*Straight-run gasoline consists of mainly straight-chain hydrocarbons and is of limited value as an automobile fuel. The reason is that straight-chain hydrocarbons cause a fuel to begin burning before it is ignited by the spark plug, which produces a knocking sound and leads to loss of engine power and eventual damage to engine.*In 1922, an American called Thomas Midgely (who also invented CFCs) found that if tetraethyl lead, Pb(CH2CH3)4, was put into petrol, particles of lead and lead oxide PbO are formed on combustion.HK government introduced unleaded gasoline through a tax differential mechanism on 1 April 1991. The goal is 77% penetration by 1995, 82% by 1996, 87% by 1997, and 94% by 1998.*Once lead enters the body, it is assimilated in the bloodstream in the same manner as calcium.

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