Ideal Gas Process
Five processes, one equation family: pVn = constant, with n = 0 isobaric, n = 1 isothermal, n = k isentropic and n = ∞ isochoric. Note the work here is closed-system ∫p·dV — a piston. Steady flow through a compressor is ∫V·dp instead, and the two order the processes opposite ways.
Pressures are absolute and temperatures are converted to kelvin internally — using gauge pressure or Celsius in a ratio is the most common error in this calculation. Specific heats are derived from the molar mass and k so that cp − cv = R holds exactly; tabulated values are rounded and do not, which would make an adiabatic process appear to exchange heat. Constant specific heats are assumed, so accuracy falls off over very large temperature swings.
A helper, not a substitute for engineering judgment. Verify against the governing standard and your own hand calculations.