It is known that the earth has a magnetic field and gravitational field around it, I wish to ask to what degree is the chemistry on the planet is influenced by these fields? How would the chemical reactions seen everyday on earth be different if the strengths of these fields were different?
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$\begingroup$ Magnetic fields affect chemistry, but not too much. Planets have typically a very weak magnetic field. Gravitational field does not affect it all. Indirectly it has effect, because attraction of the atmosphere makes its pressure. Pressure greatly affects chemistry (no pressure -> no liquids). $\endgroup$– peterhNov 18, 2020 at 19:27
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$\begingroup$ That's an ...interesting view point @John $\endgroup$– user21385Dec 14, 2020 at 8:51
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$\begingroup$ Without gravity we wouldn't have a planet to speak of. So in the sense, wholly. Once the planet has formed it does so indirectly through its geology and atmosphere. $\endgroup$– Mozibur UllahDec 16, 2020 at 7:36
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2 Answers
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How would the chemical reactions seen everyday on earth be different if the strengths of these fields were different?
Depends. If you're just talking about higher $g$ (i.e $g>9.8\ \rm{m/s}^2$) but the same atmospheric pressure, than not much will change on the surface of the earth.
If the atmospheric pressure changes, there could be changes to chemical reactions. There are several factors controlling chemical reactions. One being, obviously, the identity of the reactants. The other one is temperature. But also important is pressure. Because pressure on the surface of the earth is always 1 atm, no one really thinks or cares about pressure. No one, until it changes. That said, for any substantial change in chemistry, pressure has to change quite a lot, which would make earth uninhabitable for humans, so there would be no one to see that chemistry changed.
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$\begingroup$ Worth noting that without a magnetic field the earth might have far less of an atmosphere. $\endgroup$– JohnDec 14, 2020 at 14:44
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In the case of gravity, it depends on where you look, literally. On the surface of a typical planet gravitational fields have hardly any effect on chemistry. But if the planet is big and massive enough so that the pressure built up by gravity throughout the mass pushes it into a rounded shape, chances are that pressure is also affecting the chemistry of its rocks.
In the case of Earth, this shows up as the formation of silicate phases in the mantle that would not appear naturally on the surface, chief among them the silicate perovskites in which each silicon atom is bonded to six oxygen atoms instead of four. The illustration below shows how the silicate rocks change from the from olivine (which has the "normal" silicate bonding) into perovskite and other phases where the silicon has become bonded to the additional oxygen neighbors.
Silicates are not the only phases affected by the gravitationally generated pressure inside Earth. Carbon is affected too, leading to the (natural) formation of diamonds -- which often have inclusions of those high-pressure silicate phases trapped inside, thus providing verification of these gravity/pressure-induced phases.
