Enthalpy | Thread profile

DisplayAds("Right1"); Enthalpyof Combustion of 1 molar volume of H2(g) divided by Enthalpyof Combustion of 1 molar volume of CH4(g) = Enthalpyof Combustion per mole of H2 divided by Enthalpy of Combustion per mole of CH4 why???

Why does x/y = mx/(my)?

I guess . . . I'm just writing down what the book says . . .

I am asking why is one molar volume equal to one mole in this case at hand?

Originally posted by Integral0 I am asking why is one molar volume equal to one mole in this case at hand? It isn't :) Where does it say that the enthalpy of combustion for one mole or one molar is the same? The only thing the same, is the answer of the division, the ...

why are the two expressions above (my first post) the same or equal? My previous comment was wrong . . . I was just trying to piece together why they would be the same. "I am asking why is one molar volume equal to one mole in this case at hand?"

Please paraphrase your question --- the only thing that is clear is that you are struggling with a definition --- which definition it is, is not clear.

OK, lets look at it in the following way. Hypothetical numbers. The enthalpy of burning 2 liter one molar H2 is x. The enthalpy of burning 2 liter one molar CH4 is 2x. So H2/CH4 would be x/2x. Now, lets look at moles. The enthalpy of burning one mole H2 is 0.5x The enthalpy of burning one mole CH4 is x So H2/CH4 would be 0.5x/x, which can rewritten as x/2x....

but the first expression says "Molar volume" while the second one says "per mole"? Are they the same? What is there relation to eachother?

Paraphrasing, "Does 'molar' mean 'per mole'?" In this instance, yes. "Molar volume" does mean volume per mole, and one molar volume is a way of saying one mole. Likewise, "molar enthalpy" is the same thing as saying enthalpy per mole. For an instance in which "molar" does not imply one mole, consider 10 ml of a one "molar" solution --- "x molar" means x moles per liter of solution at ...