6- 466.64 (cont’d) e. If the column is long enough, the liquid flowing down eventually approaches equilibrium with the entering gas. At 70oC, the mole fraction of hexane in the exiting liquid in equilibrium with the mole fraction in the entering gas is 4.56x10–4mol H/mol, which is insufficient to bring the total hexane absorption to the desired level. To reach that level at 70oC, either the liquid feed rate must be increased or the pressure must be raised to a value for which the final mole fraction of hexane in the vapor is 2.63x10–4or less. The solution is min1037 mm Hg.P=6.65 a.Intersection of vapor curve with yB=030.at T=°⇒10413% B(l),C 87%T(l)b.( )( )100 C0.24 mol B mol liquid , 0.46 mol B mol vaporBBTxy=°⇒==Basis: 1 mol0.30 mol B(v)/molnV(mol vapor)0.46 mol B(v)/molnL(mol liquid)0.24 mol B(l)/molBalancesTotal moles:B:..molmolmol vapormol liquid1030 046
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