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What is the Earth's composition (by compounds not elements)?

  1. Jul 11, 2016 #1
    I have tried looking for papers on the composition of earth, but none of them seem to list the abundance of compounds. They just list the elements. So, what are the abundances of the most common compounds, by mass and/or percent of Earth?
     
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  3. Jul 11, 2016 #2

    mfb

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    As the mantle has 2/3 of the mass: Googling "earth mantle chemical composition" gives this article which summarizes several estimates of the chemical composition of the mantle on page 3. The outer core is liquid and doesn't have well-defined molecules, and the inner core should be more like a massive alloy where the concept doesn't make sense either. The crust is complicated, but I guess the main components can be found in some publications as well.
     
  4. Jul 11, 2016 #3

    Borek

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    As mfb wrote - the main problem is that in many places it is hard to speak about "compounds". Many minerals are what we call a solid solution - mixture of several compounds forming a continuous solid (one that doesn't have to have a uniform composition!). Most rocks in the crust and mantle are composed mainly of silicates and if anything, I would assume silicates are the most common "compounds".
     
  5. Jul 12, 2016 #4
    Since the planet is c.a. 3/4 ocean, I think it is safe to say dihyrogen monoxide is one of the more plentiful compounds.
     
  6. Jul 12, 2016 #5

    Borek

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    Definitely not.

    Definitely not.
     
  7. Jul 12, 2016 #6

    phyzguy

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    Seconding Borek's "definitely not". The oceans are a very thin skin on the surface of the Earth.
     
  8. Jul 12, 2016 #7

    mfb

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    To add numbers: As 0.45 of the mantle is SiO2 and the mantle is 2/3 of the mass of Earth, 30% of the total mass is SiO2 in the mantle (there is also SiO2 in the crust). The whole crust has 0.5% of the mass of Earth, and the mass of the oceans is just 0.025% of the total mass of Earth.

    SiO2 beats H2O by a factor of 1000.
     
  9. Jul 12, 2016 #8

    TeethWhitener

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    Last edited by a moderator: May 8, 2017
  10. Jul 12, 2016 #9

    mfb

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    Forgot "in the oceans" in my comment.

    SiO2 in the mantle beats H2O in the oceans by a factor of 1000.
     
  11. Jul 12, 2016 #10

    ProfuselyQuarky

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    Shouldn't the Earth's atmosphere be considered as well? I'm not saying that the percentage of compounds within the atmosphere would surpass that of the mantle and whatnot--I'm just asking whether the atmosphere should be considered as part of "Earth".
     
  12. Jul 12, 2016 #11

    Borek

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    That's what I would do. Not that it will change things by much (perhaps for the noble gases?).
     
  13. Jul 12, 2016 #12

    mfb

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  14. Jul 13, 2016 #13
    My bad, I was thinking of the surface, not the whole planet.
     
  15. Jul 13, 2016 #14

    ProfuselyQuarky

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    That's what I thought.

    Edit: I hope that pun was intended.
     
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