General chemistry - piston vs flask

[Monkeymaniac]

---

Members do not see this ad.

I had a simple question reagarding piston vs flask used in testing La Chetalier's principle.

TBR states that for an enclosed piston, P is constant while V is subject vary, where as for flask, V is constant but P may vary.

Does this always hold? Thanks in advance!

 

[PiBond]

I had a simple question reagarding piston vs flask used in testing La Chetalier's principle.

TBR states that for an enclosed piston, P is constant while V is subject vary, where as for flask, V is constant but P may vary.

Does this always hold? Thanks in advance!

"always" is a dangerous word to use in science. a rigid container (like a flask) is isochoric (constant volume) while a piston is generally considered isobaric (constant pressure) because of its ability to move up and down. if we were to heat a gas in a rigid container like the flask then the pressure would necessarily have to increase under the ideal gas equation. in contrast, if we were to heat a gas in a piston then the the volume of the piston would expand as it did work while pressure remained constant. however, you may come across a situation where the experimenter locks the piston and therefore it would no longer expand