Amixture of 5 mol% butane and 95 mol% air is fed to a sieve-plate absorber containing 8 ideal plates at 1 atm and 15 °c. the absorbing liquid is a heavy, nonvolatile oil. the recovery of butane is to be 95%. the vapor pressure of butane at 15 °c is 1.92 atm. assume raoult's and dalton's law apply. 2. (a) calculate the minimum amount of oil needed for this operation per 100 kmol/h of the gas mixture. (b) calculate the amount of fresh oil used in this operation (c) when the column pressure is increased to 3 atm, calculate the recovery of butane when the same amount of oil in (b) is used. [lf you don't have the answer for (b), use l 235 kmol/h.]