A heat exchanger is to be constructed in which air (assume Cp=7 Btu/lbmol 0F) is to be heated from 70 to 200 0F by another stream of air, originally at 350 0F. Equal amounts of heated air and heating

A heat exchanger is to be constructed in which air (assume Cp=7 Btu/lbmol 0F) is to be heated from 70 to 200 0F by another stream of air, originally at 350 0F. Equal amounts of heated air and heating air are to be used. Assume that heat losses from the exchanger are negligible. Calculate a) the entropy change of the heated air; b) the entropy change of the heating air; and c ) the total entropy change.