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I'm doing a little bit of research for an experiment that I want to conduct in science and it relies on that one question. So,

  • Is it possible to separate a $CO_2$ molecule into a $C$ and $O_2$?

    • Has this been done before, and what were the results? Is this even feasible?
    • How much energy is required to split the $CO_2$ molecule into a $C$ and $O_2$?
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    $\begingroup$ Post this is chemistry stack exchange $\endgroup$ – ShankRam Dec 14 '15 at 16:35
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    $\begingroup$ @ShankRam: scientifically this problem has aspects that strongly belong in physics: the bonds that keep molecules together are a Quantum Mechanical phenomenon. $\endgroup$ – Gert Dec 14 '15 at 16:51
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    $\begingroup$ I'm voting to close this question as off-topic because OP shows insufficient research efforts. $\endgroup$ – user36790 Dec 14 '15 at 17:06
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    $\begingroup$ This is a highly relevant question and a hot research topic. Creating such an experiment in lab efficiently (Artificial photosynthesis) have high potential in constructing energy efficient solar cells. For e.g. have a look at this. I strongly oppose to voting this down as the search for an answer could prove to be a milestone. $\endgroup$ – Sathyam Dec 14 '15 at 17:37
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    $\begingroup$ It's definitely chemistry; it's not asking for any physical insight. $\endgroup$ – Mozibur Ullah Dec 14 '15 at 18:30
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By heating any substance to a sufficiently high temperature it will decompose into its constituent atoms because chemical bonds do not survive the inter-atomic movements between the nuclei, at these temperatures.

That part of quantum physics we usually call Chemistry thus has a fairly limited temperature window: very broadly speaking (because it depends strongly on the type of molecule) above $5000\:\mathrm{K}$ all molecular structure (chemical bonding) has been lost and substances become 'atom soup'. That's why in very hot bodies (like stars) no chemical structures exist.

Regards the energy needed to decompose $\mathrm{CO_2}$, simply look up the Enthalpy of Formation of that substance and invert the sign. In reality, thermal decomposition will need more Enthalpy because of heat losses at such high temperatures.

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Q: Is it possible to separate a CO2 molecule into a C and O2?

A:Yes, one can split any molecule down to its constituents. In other words, there is no chemical compound on earth that cannot be split into constituent atoms.

Q: How much energy is required to split the CO2 molecule into a C and O2?

This slightly depends on what kind of carbon you are talking about. Please check the wikipedia article for different allotropes of carbon.
A back-of-an-envelope type of calculation:
- to break one C=O bond in CO2 molecule requires 800 kJ/mol
- to form a O=O bond in O2 molecule releases 495 kJ/mol
- the cohesive energy of diamond is roughly 7.9 eV/atom (762 kJ/mol)

1600-495-762=343 kJ/mol

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