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Article: Simplify your thermodynamics.
- Article from:
- Canadian Chemical News
- Article date:
- November 1, 1994
- Author:
CopyrightCOPYRIGHT 1994 Chemical Institute of Canada. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Changing the traditional sign convention in thermodynamics can eliminate confusion and erroneous results
In the traditional thermodynamics literature, the first law, which expresses energy conservation, is written as
[Delta]U = Q [W.sub.e] (1)
for closed (non-flow) systems and as
[Delta]U + [Delta][E.sub.k] + [Delta][E.sub.p] = Q - [W.sub.s] - [W.sub.e] (2)
for open (flow) systems. The symbols are defined separately. The usual sign convention is such that Q is positive if heat is supplied to the system and W is positive if the system produces work. (Historically, this sign convention arose from the application of thermodynamics to heat ...