CHM 310 LEC2
The story of how the atmosphere came to be and in particular how carbon plays a
We are going to start with the composition of gases
Ppm parts per million is a mixing ratio, no different than percentage
We are interested in where does that carbon comes from and why is it so imp
4.5 billion years ago it was thought that the solar system formed and the universe
was about 17 billion years ago so the solar system started initially probably a star
because it would have lived its life and probably
Why is there O2?
Why is there massive amounts of N?
Where the C and the fossil fuels emerged?
1. Atmopshere: N2 78%, O2 21% , Ar 1%, few percent water (Dry Atmsph)
2. 390ppm 0.039% CO2
3. Where does this C come from?
4. 5 billion years ago: the soil wasn’t formed
5. Universe is 17 billion, solar system started after the beginning of the universe
6. Sun was formed, the planet was formed 4.5 billion years ago. Inert gases are
low on earth relative to sun. we are now having a secondary atmosphere.
7. Primary atmosphere lost due to solar wind or large impact by the moon.
8. Earth have a secondary atmosphere – strong wind which blew away the primary
9. With a composition in the planet which is not disismlar to the sun
10. Jupiter, Saturn there’s a lot of H in the planet, in earth there isn’t
11. In earth’s composition there is lot of inert gases.
12. Primary Atmosphere – Thicker. Saturn and Jupiter have this kind of atmosphere.
There is lot of H in the atmosphere.
13. Secondary Atmosphere – Earth, relatively thin. Not that much of H.
14. How did this atmosphere evolve? The secondary atmosphere?
15. Two possible mechanisms
a. Volcanic – volcanoes communicating compositer gases to the atmosphere
from the inside of the earth. If you sample a volcanoes you can find CO2,
SO2, H2O, fairly reduced molecules as well, like HCl. HF.
b. Asteroid/ meteorite influence- the composition of the asteroid are ice and
no of them have carbonated rocks. They have C in them already. Supply
the volatiles. Together they started to give you secondary atmosphere.
16. Venus – average surface temperature 470Celcius
17. Earth – 15 degrees
18. Mars - -150 celcius
19. Venus Mars and Earth are like the same size, pretty close, but have extremely
21. Earth: condensation of gases. Between Co2 and H2O, H2o condenses best.
22. Start to form oceans on the earth Water, vapored in the atmosphere intitally,
23. Water vapored itself a very strong green house gas. By allowing the water to
condense you don’t fill up GHG, and form the ocean CHM 310 LEC2
24. Co2 is a soluble gas, can dissolve within water. Relatively high soulbility
25. Co2 being exposed to water carbonic acid dissociates to bicarbonate
dissociates to carbonate
26. Physical solubilty of co2 in water is higher than N2 , O2.
27. Calcium Carbonate found in sedimentary rocks. Almost solid,
28. Lobsters shell is