A diving experiment is to be performed with a mixture of helium and air at a total pressure of 50.0 psia. The composition must be such that the partial pressure of oxygen in the compressed mixture is the same as that in air at standard pressure and temperature (14.7 psia and 70.0°F). Assuming a closed system and ideal gas behavior, determine
a. The work required to isentropically compress 2.70 lbm of the mixture from 14.7 psia, 70.0°F to 50.0 psia.
b. The heat transfer required to aergonically cool the compressed mixture back to 70.0°F again.