Is Log of Molecules a Thermodynamic State Variable?

[keith river]

Is log (no of molecules) a state variable? I know that the no of molecules are a state variable so I assume the logarithm of this is still a state variable. Am I right?

 

[dextercioby]

In what context did you bump into this question ? Why is ln N there ?

 

[keith river]

It was just a question I found in a thermodynamics question book. The full question is
"State whether these are state variables or not... (list of quantities)... logarithm of number of molecules"

 

[dextercioby]

What is a state variable ? You need to be sure about the notions before attempting an answer.

 

[keith river]

State Variables are parameters which describe a thermodynamic system.
Some are inherent in the system (eg specific heat capacity) and some we can control (eg heat capacity)

I suppose since we can control N then ln N is to an extent controlled, but I don't know if it counts as a state variable.

Also (quick question to check an answer I made) is the melting and boiling points of a material a bulk property state variable. As they cannot be controlled but still tell us about the system?

 

[dextercioby]

I would say that a state variable must be a physical quantity and not some mathematical function of it.

As for the melting and boiling point, what do you mean by <cannot be controlled> ?