0 Members and 1 Guest are viewing this topic.
I know it doesn't. Just wanna know why CO2 doesn't support combustion, though to remind you it does burn readily with burning Mg, Na and K.So my question is why it doesn't do the same with other elements and/or compounds.Please explain the Thermodynamics as well as the mechanistic part of the question.And am expecting a very chemist-type answer.
If that is the case then it must not react with burning magnesium.....as i had already mentioned.And what are the thermodynamic stats relating to combustion with CO2, if any.
I'm not sure what Tommya300 is on about, I think he doesn't understand that Mg will burn just fine in pure CO2 to give C and MgO.The reason that things like coal burn is that the reaction of coal with oxygen is exothermic. The products of combustion (mainly CO2) are more stable than the starting materials.Magnesium also burns because the reaction of magnesium with oxygen to give MgO is also very exothermic.This is because the energy released when the Oxide ions and magnesium++ ions come together to form the solid is more than the energy required to turn the oxygen and magnesium into ions in the first place.If you look at the case of burning carbon the energy released is due to the greater bond energy of CO2 compared to the bond energies of the O2 and the Carbon.The energy released from burning magnesium is so large that it is "worthwhile" to decompose CO2 to C and O2. In most cases the energy released on burning isn't great enough to make the overall reaction with CO2 worthwhile.In effect to get something to burn in CO2 you need to supply the energy needed to split it into C and O2; if you don't get enough energy back by burning that something, then the reaction grinds to a halt.