Is Total Molar Concentration Constant in an Isothermal System?

AI Thread Summary
In an isobaric isothermal system, total molar concentration remains constant due to the dynamic equilibrium between phases, such as solid naphthalene and its vapor. While the perfect gas equation (PV=nRT) indicates that volume (V) can change, the number of moles (n) adjusts accordingly to maintain equilibrium, ensuring that total molar concentration does not fluctuate. The desorption of naphthalene atoms into the gas phase contributes to this balance, allowing for changes in volume without altering the total molar concentration. The equation C=CA+CB is valid under constant temperature and pressure conditions, but the underlying principle of equilibrium holds true beyond these constraints.
mech-eng
Messages
825
Reaction score
13
how can we understand total molar concentration remains constant in a isobaric isothermal system? if it is from perfect gas equation pv=nrt although p and t are constant but v isn't constant so since mol number can be change over volume, total molar concentration may change.it is a situation of a tube with one end is surrounded by gaseous nitrogen and one end is closed with a solid naphthalene in equilibrium with its vapor.
 
Engineering news on Phys.org
Total molar concentration remains constant because n can change
probably: if it is solid napthalene in equilibrium with its vapor, then napthalene atoms can desorb and enter the gas phase to maintain equilibrium. so if volume changes, n will change correspondingly
 
But it must always be constant which is equal to 1 so we shouldn't limit the situation to the isobaric isothermal case.Am I right? is C=CA+CB always true or only for at constant
T and P
 
Last edited:
Back
Top