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On Mars carbon dioxide is abundant. It is plausible to utilize a fuel in an engine that can use carbon dioxide as an oxidizer? I know this is a strange inquiry, but could a engine be made to use $\ce{CO2}$ in the martian atmosphere the same way most engines consume $\ce{O2}$ on Earth?

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Usually when we say something "burns", it's being oxidized. In the case of carbon dioxide only the oxygen can be oxidized, by displacing it as the element; that requires fluorine or a sufficiently powerful fluorinating agent.

Carbon dioxide supports combustion, acting as the oxidizer instead of being oxidized, with some active metals such as magnesium. Thus

$\ce{2 Mg + CO_2 -> 2 MgO + C}$

Such reactivity is why special reagents are needed to extinguish burning active metals.

Addendum:

The comments indicate that the OP is interested in burning fuel on Mars. Absent any active metals like magnesium in the oxide-rich and still water-bearing environment on Mars, it is not practical to use carbon dioxide for combustion. Better is to bring some water along or extract it from underground, electrolyze it with solar power, and re-burn the hydrogen and oxygen.

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  • $\begingroup$ How come this is no longer accepted? I assumed that there had been a better answer but I find that none exists. Thank you. $\endgroup$ – Oscar Lanzi Mar 9 at 7:24
  • $\begingroup$ I need to see if there are other chemical ways this can be done. Now that it has been reopened I will accept it if no one else answers. My question originally had grammars issues, but @A.K. thanks, fixed it. Maybe it will now start getting up votes. $\endgroup$ – Muze Mar 13 at 18:42
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    $\begingroup$ I like the suggestion to think outside the box and use fluorine as an oxidizer. $\endgroup$ – A.K. Mar 14 at 0:34
  • $\begingroup$ Tempting, but how? I assume you can electrolyze fluorides with solar power, but are these known on Mars? $\endgroup$ – Oscar Lanzi Mar 14 at 0:38
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    $\begingroup$ You would probably have to brink tanks of fluorine to Mars with you. $\endgroup$ – A.K. Mar 14 at 19:05

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