Question

Is the relation "delta h(enthalpy) = m * Cp,avg * delta T" restricted to constant pressure process only, or can it be used for any kind of process of an ideal gas? detailed and easy-to-understand reason included, please.

Answer 1

This relation can be uswed to determine the enthalpy change for any gas (real or ideal), undergoing a constant pressure process. however, if the gas is ideal, this equation can be used to determine the enthalpy change of the gas irrespective of the process that it is undergoing.

Reason:

generally, the enthalpy change is a function of temperature and pressure. i.e.

therefore,

using the maxwell's equation and the defination of specific heat, the equation transforms into

so for any constant pressure process, dP=0, therefore equation just becomes:

however, let an ideal gas undergo any process which is not constant pressure.

for an ideal gas, we know:

and,

hence,