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Produce Methane Via CO2 + H2O ?

  1. Jun 17, 2014 #1
    it is known that the standard combustion enthalpy of methane is -882 kJ/mol

    CH4 + 2 O2 --> CO2 + 2 H2O Hc = -882 kJ

    based on hess's law, if a reaction is reversed, so does with the enthalpy

    CO2 + 2 H2O --> CH4 + 2 O2 Hc = +882 kJ

    which makes the reversed reaction become endothermic. if the system provides enough heat for the reaction (+882 kJ) to be absorbed, would the reaction just simply happen ?? or is there anything else to be considered ?

    help me plz……
  2. jcsd
  3. Jun 17, 2014 #2


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    Staff: Mentor

  4. Jun 17, 2014 #3


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    You should also take in mind that this is not the only possible reaction. Especially you will also get carbon monoxide, CO, and elementary carbon. That's why you will probably never get methane when heating CO2 and water.
  5. Jun 17, 2014 #4
    wait…..the enthalpy of sabatier process is negative, while the reversed-reaction above is positive. so i think it is quite different.

    if i increase the temperature, the equilibrium will shift to the right (product region). increasing pressure would not affect the equilibrium since the product and reactant region have the same reaction coefficient. and the need of catalyst (?).

    i have read about how fuel could be produced if carbon dioxide and water reacted with sunlight + catalyst (it's called 'artificial photosynthesis'), but it's a bit arduous to find and synthesize the appropriate catalyst.

    some people reported that they found methanol and formic acid, instead of methane.

    i just wanted to know if it's possible to carry out the reversed-reaction without sunlight and catalyst, based on thermochemistry approach, not photochemistry approach. (by provide sufficient heat or find any catalyst maybe ?)

    what should i seek ?

    thank youuu
    Last edited: Jun 17, 2014
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