There are two sign conventions:
1. The so called engineering sign convention
2. The international sign convention.
The first convention is simple to follow from the point of view of applications. In this convention, we give heat as input to an enginge and expect it to deliver work as out...
If a chemical reaction involves (theoritically) transformation of chemical energy into any form of energy other than heat (electrical energy, for example), such reaction is deemed to be reversible.
Therefore, the question we are left with is about reactions involving energy transformations...
First law of thermodynamics applies to all processes - both cyclic and non cyclic.
There are three types of systems in thermodynamics:
1. Open system - A system that can exchange both matter and energy (in the form of heat and
work), with surroundings.
2. Closed system - A system...
No doubt, we have been designing and operating equipment and processes in everyday practice. However, for each of those designs, we can have several alternate possible designs, the design takes several other factors (such as financial aspects) into consideration. Suppose we ask if a given design...
Since you are also referring to chemical reactions as examples of processes under discussion, the following might help.
In the study of chemical reactions, besides thermodynamic considerations, we study kinetics of reactions to arrive at mechanism (Path followed by the reaction in going from...
This is the reason why reversibility is a mental construct, to imagine it in practice we invoke that quasistatic process and use all the jargon of infinitesimal differeneces etc.
Think for yourself how one can have massless frictionless pulleys, pistons etc to carry out expts in mechanics...
The references imply this: For quasistatic processes the difference in the values of the intensive properties of the system and surrounding differ by infinitesimal amounts. To that infinitesimal extent the process would be irreversible; only in the case the differences are zero reversibility is...
For a quasistatic (reversible) process we need to satisfy the condition Pext= Psym. When friction is present it is impossible to satisfy this condition.
The speed (or time rate of change) of a process (slow enough of fast enough etc) does not and should not enter thermodynamic arguments -...
The last para is good enough.
But I saw the Van de Graaf ball and capacitor in a different way.
In the former the whole charge lies on the outer surface while the inner surface is free of any charge. Charge separation is over a very small thickness of the ball. Therefore, even for a small...
I was referred to this thread by Chet.
The points 1 and 4 above need a comment.
1. Since we are interested in a process of irreversible adiabatic expansion (or compression) of an ideal gas, it is not necessary that the external pressure (Force on the pistion) be constsnt. The necessary...
The irreversible process involving expansion of a gas with friction is more complicated than necessary. A simpler process to understand the concept of reversible and irreversible processes would be to consider either expansion with pressure of the surroundings lower than the pressure of the...
The irreversible process involving expansion of a gas with friction is more complicated than necessary. A simpler process to understand the concept of reversible and irreversible processes would be to consider either expansion with pressure of the surroundings lower than the pressure of the...