Question

Why we have to define the heat capacity of gases under constant pressure and constant volume condition?

Answer 1

The heat capacity of a defined system is the amount of heat needed to raise the system's temperature by one degree. This is different when the heat is supplied under constant pressure and constant volume (no expansion) condition.

During constant volume, no expansion of the fluid occurs. But in constant pressure some amount of work is utilized for expansion process. At constant pressure, some of the energy you put in goes into raising the temperature (internal energy) and some of it goes into doing work by expanding the ideal gas.

This applies for compressible fluids ( gas) alone. Liquids and solids can be considered to be incompressible since the amount of work utilized for expansion is very very negligible.

For solids and liquids, Cp = Cv = C

No distinct heat capacity values at constant pressure and temperature.




HOPE THIS HELPS!!!

Answer 2

Explanation:

That pressure is called atmospheric pressure, or air pressure. It is the force exerted on a surface by the air above it as gravity pulls it to Earth. ... Oneatmosphere is 1,013 millibars, or 760 millimeters (29.92 inches) of mercury.Atmospheric pressure drops as altitude increases.