Does The First Law Of Thermodynamics Univocally Define The Relative Proportions Of Heat And Work?
Posted by admin on November 24, 2009 under Thermodynamics | 
2 Comments to Read
Does the first law of thermodynamics univocally define the relative proportions of heat and work that are involved
in a given variation of internal energy of a system? Explain.
shorti3 said,
No. The 1st Law can be expressed as Q-W=deltaU if changes in other state energies such as potential and kinetic are negligible.
So, for a given change in state, there is a fixed value of deltaU. The 1st Law constrains Q and W but does NOT constrain their relative magnitudes. For example, let’s say deltaU is 1000 kJ. One path for this change in state could result in Q = 1000 kJ and W = 0 kJ resulting in a ratio of Q/W = infinity. Another path might result in Q = 2000 kJ and W = 1000 kJ. In this case, Q/W = 2. The RELATIVE PROPORTIONS are not constrained by the 1st Law.
Dr. B from LearnThermo.com said,
No. The first law allows interconversion of heat and work.
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