Presentation on theme: "CH217: King 1 Where do we start? –Create the Universe –Form the Earth and elements –move the elements into their correct positions –build the atmosphere."— Presentation transcript:
CH217: King 1 Where do we start? –Create the Universe –Form the Earth and elements –move the elements into their correct positions –build the atmosphere and oceans
CH217: King 2 The BIG BANG The Universe was created 15 billion years ago in one BIG BANG How do we know? Start with the atom
CH217: King 3 ENERGY Nucleus
CH217: King 4 ENERGY Nucleus } E = hv
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6 Elemental Absorption Every element has a characteristic absorption spectra - (ICP) Wavelength 400 nm 700 nm
CH217: King 7 Spectrum of the Sun
CH217: King 8 From the magnitude of the shift we can calculate the speed of the star. The more distant stars are moving the fastest. From distance and velocity information -> TIME 15 billion years! Wavelength 400 nm 700 nm
CH217: King 9 At the Start Big Blob of Neutrons (N) Protons and electrons BANG 12 Minutes
CH217: King 10 Now we are COOKING Fusion produces heat E = mc 2 1 gram of hydrogen will produce 6.3x10 11 j of heat. Enough heat to boil 2 million liters of H 2 O Compare this to our terrestrial energy consumption.
CH217: King 11 C
CH217: King 12 This process stops at iron-56
CH217: King 13 Elements H-1 through Fe-56 Supernovae Explosion Second Generation Star H through Fe and n
CH217: King 14 Elements H-1 through Fe-56 Supernovae Explosion Second Generation Star H through Fe and n
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CH217: King Proton Number Neutron Number 14 C 14 N e- Beta Decay
CH217: King Proton Number Neutron Number 40 K 40 Ar e- Electron Capture
CH217: King Proton Number Neutron Number 234 Th 238 U 4 He Alpha Decay
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CH217: King 20 Review of Element Formation Big Bang Nuclear “Cooking” - Fusion Neutron Capture What is the end result?
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CH217: King 24 What about the Earth?
CH217: King 25 Another look at the earth on a linear scale. Where did all the other elements go? H, He, C, N?? They got BLOWN AWAY This leaves just Si, Mg, Fe, and O
CH217: King and just for fun
CH217: King 27 Formation of the Earth The earth started as a hot molten blob of metal and oxygen As the blob cooled, density differences of the original components drove an elemental segregation. Metallic iron - The Earth’s core Mg, Fe, and Si oxides - The crust How do we know? We know from earthquake seismology
CH217: King 28 A Slice of the Earth Inner Core Outer Core Mantle
CH217: King 29 A Slice of the Earth Inner Core Outer Core Mantle 2900 km earthquakes travel as shear waves or compressional waves
CH217: King 30 shear waves only pass through SOLIDS (mantle) So we have a “liquid” iron core. This has important implications for other elements –Ni, S, Au, Pt, Ag, Pb dissolve in the liquid iron What is left is Mg, Si oxide mantle. The mantle is not really solid, but really a “putty” that is kept warm by the radioactive decay of 40 K, 235 U, 238 U, and 232 Th. The heating of the mantle drives convection cells.
CH217: King 31 Inner Core Outer Core Lower Mantle Crust The mantle melt cycle (subduction/formation) enriches the crust further in Si, Na, K, Ca, and Al
CH217: King 32 What about the Oceans and the Atmosphere? The Earth is about 0.5% water. Where did it come from? The source of water in the early Earth is poorly understood...we are lucky that it arrived. The gravitational attraction of the Earth retained almost all of the water. Surface water puts important constraints on global temperature! o C.
CH217: King 33 Controls on CO 2 CO 2 is controlled by a global scale feedback loop with a time scale of >10,000 years Consider the following reactions:
CH217: King 34 Controls on CO 2 CO 2 is controlled by a global scale feedback loop with a time scale of >10,000 years Consider the following reactions: Generic Weathering Reaction Generic Precipitation Reactions Generic Mantle Reactions
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CH217: King 36 Lets work with units CO 2 (g) %, This is a mixing ratio O % N % Ar0.93% PV= nRT, average mass gas g/mol %, 00/0, ppm, ppb
CH217: King 37 Pressure Atmospheric Pressure is a force: kg/m 2 P 0 = Mass(atm g)/4( r 2 r = 6.37x10 6 m P 0 = Pa P h = P o e -Mgh/RT M = kg/mol R = J/mol K g = 9.81 m/s 2 Scale height 5-6 km