Entropy of mixing for ideal gasesWhen a person has emphysema, the inner walls of the air sacs in the lungs weaken and eventually rupture creating one larger air space instead of many small ones. This reduces the surface area of the lungs and, in turn, the amount of oxygen that reaches the bloodstream. For patients with severe emphysema, oxygen$-$enriched air is provided to help relieve the symptoms.Consider the case where oxygen$-$enriched air is made by adding pure oxygen at atmospheric pressure $(101$ kPa$)$ to ordinary air $(21$ mole$\%$ oxygen$).$ A metering valve blends the two streams isothermally $(25\backslash$deg C$)$ and adiabatically to produce a mixture with $35$ mole$\%$ oxygen at a rate of $0\mathrm{.}5$ mol$/$minute of mixture. Assume ideal gas behavior for this problem.a$.$ How many moles of pure oxygen gas must be added to each mole of air?$($Hint: You need to set$-$up a continuous mass balance problem with the metering valve blending the air and pure streams to produce the $0\mathrm{.}5$ mole$/$min $35$ mole$\%$ oxygen.$)$b$.$ At what rate in unit W$/$K is entropy generated during the mixing process? $($Hint: Air canbe considered as a pure substance for this problem, so you can let A $=$ air and B $=$oxygen$)$