Combustion of Methane

[Gabriel Wolf 3I]

I was confused on how we can find the combustion of methane under standard conditions. Isn't an initial heat that is above 25C required to start combustion? How would we factor that in? How do you calculate the standard enthalpy of reactions that are unfavorable except in very extreme conditions?

[Sammy Liu]

The standard reaction of formation does not require a specific temperature. In fact, it just requires the substance be in their most stable form, whatever this may be.

You're talking about the standard reaction enthalpy. This scenario requires a standard state for the enthalpy to be measured. For gases, it is a pressure of 1 atm. For pure elements that are liquids or solids, the standard state is a pure sample at 1 atm and at a temperature of interest, which is usually 25ºC. Because methane is a gas, it does not need to be at 25ºC.

Hope this helps!