- #1
burakumin
- 84
- 7
During my studies I failed to understand thermonynamics and compared the whole subject to black magic. This frustrated me a lot. Years later I tried to restudy it by myself reading sources with less conventional approaches. I had finally come to believe I could make sense of it. But re-reading certain articles (for example on wikipedia) leave me confused even about basic concepts like thermodynamical equilibrium. I feel bit discouraged.
I can find at least two distinct definitions for thermodynamical equilibrium depending on the sources. Sometime these definitions are even introduced in the same article as implicitly equivalent. A system is in equilibrium iff:
1) it does not exchange energy or matter with its surrounding and its macroscopic properties (state functions) does not change over time;
2) it is as a uniform temperature (a situation called thermal equilibrium) a uniform pressure (mechanical equilibrium) and constant concentrations (chemical equilibrium)
Let's consider a simple system that consists of two gases in two distinct containers that have adabiatic, impermeable and unmovable boundaries between each other and with their surroundings. Let's suppose those gases are chemically different, have different temperatures and different pressures.
Is such a system in equilibrium or not ? To me it perfectly fits definition 1 (which I had always thought as the valid definition of equilibrium) but clearly fails to fullfil conditions of definition 2. So I cannot see how someone could say these definitions are equivalent
I can find at least two distinct definitions for thermodynamical equilibrium depending on the sources. Sometime these definitions are even introduced in the same article as implicitly equivalent. A system is in equilibrium iff:
1) it does not exchange energy or matter with its surrounding and its macroscopic properties (state functions) does not change over time;
2) it is as a uniform temperature (a situation called thermal equilibrium) a uniform pressure (mechanical equilibrium) and constant concentrations (chemical equilibrium)
Let's consider a simple system that consists of two gases in two distinct containers that have adabiatic, impermeable and unmovable boundaries between each other and with their surroundings. Let's suppose those gases are chemically different, have different temperatures and different pressures.
Is such a system in equilibrium or not ? To me it perfectly fits definition 1 (which I had always thought as the valid definition of equilibrium) but clearly fails to fullfil conditions of definition 2. So I cannot see how someone could say these definitions are equivalent