Integrating Chemistry into SCI 210 The Dynamic Earth Andrea Koziol, Dept. of Geology.
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Transcript of Integrating Chemistry into SCI 210 The Dynamic Earth Andrea Koziol, Dept. of Geology.
![Page 1: Integrating Chemistry into SCI 210 The Dynamic Earth Andrea Koziol, Dept. of Geology.](https://reader035.fdocuments.in/reader035/viewer/2022070407/56649e295503460f94b171e6/html5/thumbnails/1.jpg)
Integrating Chemistry into SCI 210 The Dynamic Earth
Andrea Koziol, Dept. of Geology
![Page 2: Integrating Chemistry into SCI 210 The Dynamic Earth Andrea Koziol, Dept. of Geology.](https://reader035.fdocuments.in/reader035/viewer/2022070407/56649e295503460f94b171e6/html5/thumbnails/2.jpg)
Chemistry in Earth science
• Chemical concepts actually quite pervasive
• Touched on in lecture in a number of instances
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Emphasized in these areas
• Minerals• Energy and mineral resources• Greenhouse effect (action of CO2
molecule)• Chemical weathering• H2O changes of state, latent heat (clouds
and weather)• Ozone in the stratosphere• Numerical dating with radioactive isotopes
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Crystalline nature
• Orderly internal arrangement of atoms in a lattice
• A specific pattern that repeats at regular intervals
minerals
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Oil and gas
• Oil and gas are hydrocarbons: chains or rings of C and H
• React with O2 to form gas and heat energy
• For example:
• 2 C8H18 + 25 O2 = 16 CO2 + 18 H2O + heat energy
Natural resources
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This is the Greenhouse Effect
• Water and CO2
molecules absorb this heat energy
• The atmosphere is heated from the ground up
• This heat stays in the atmosphere
Infrared
H2O CO2
Greenhouse effect I
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Chemical Weathering
• Chemical weathering: destruction or altering of minerals when rock comes in contact with water solutions or air.
• Examples:
• Dissolution by water or carbonic acid, oxidation, reaction to new minerals
weathering
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Chemical weathering examples
• Dissolution by carbonic acid: CO2 dissolves in H2O (rain) to form weak carbonic acid (H2CO3) which attacks limestone, marble
weathering
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Moisture and Clouds
• It’s about H2O and changes in state:
• Ice --- liquid --- water vapor
Atmosphere II
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Latent heat (hidden heat)
• Latent heat: heat added that is not associated with temperature changes. It is energy absorbed or released during a change in state.
• Storing this latent heat, moving it around, is important!
Atmosphere II
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Global: CO2, Greenhouse Effect, Global Warming
• Today: CO2 concentration in our atmosphere is >0.036 % or 360 PPM
• If less CO2: cooler temperatures and cooler climate
• If more CO2: warmer temperatures and warmer climate
Global climate change
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Most up-to-date infoGlobal climate change
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What is ozone?
• Oxygen molecule: O2
• Ozone molecule: O3
• Very little ozone in troposphere
– What is there is a pollutant
• 90% of ozone is in the stratosphere
Ozone
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How this works, cont’d.
• O3 + UV light energy = O2 + O (UV light totally absorbed)
• O2 + O recombine rather
quickly
• Reaction repeats
• UV light from Sun almost totally absorbed
Ozone
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Parents and daughters
• Starting radioactive isotope: parent
• After decay, it’s different: daughter
• The number of protons, neutrons have changed by radioactive decay
• Example: carbon-14 (6 protons, 8 neutrons) decays to nitrogen-14 (7 protons, 7 neutrons)
Numerical dating
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Rate of decay• How a parent atom decays, and rate of
decay is fixed.• Rate of decay doesn’t vary, no matter
what physical or chemical conditions the isotope is in.
• Every parent atom produces one kind of daughter
• So: look at amount of parent left, amount of daughter present.
Numerical dating
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Now: radioactivity
• Radioactive decay is not linear.
• It is exponential. (see fig.10.14, decrease in # of parent isotopes as time passes)
Numerical dating
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Radioactive decay example• Start with 160 parent atoms in our sample. How
much time has passed?• T = 0 half-l. 160 parents 0 dau.• T = 1 half-l.80 parents 80 dau.• T = 2 half-l. 40 parents 120 dau.• T = 3 half-l. 20 parents 140 dau.
• Look at ratio of parents to daughters to tell time.
Numerical dating