standard formation enthalpy in Combustion

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Joyce 3H
Posts: 21
Joined: Fri Sep 26, 2014 2:02 pm

standard formation enthalpy in Combustion

Postby Joyce 3H » Tue Jan 27, 2015 12:04 am

In calculating standard reaction enthalpy in combustion, which is exothermic reaction, why do we always use the standard formation enthalpy of liquid form of water instead of the gaseous one?
Thank you !

Niharika Reddy 1D
Posts: 127
Joined: Fri Sep 26, 2014 2:02 pm

Re: standard formation enthalpy in Combustion

Postby Niharika Reddy 1D » Tue Jan 27, 2015 12:09 am

Unless stated otherwise (as in problem 115 where it says the products of the combustion reaction are gaseous), the products of the combustion of an organic compound are carbon dioxide gas and liquid water, and any nitrogen present is released as nitrogen gas (N2). If any other products are formed, the problem should specify that. This is found on the bottom of page 267 in the textbook.


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