Example $8\mathrm{.}16$ : A methanol $($A$)$ water $($B$)$ solution containing $50\%$ by weightmethanol at $300$ K $(270$ C$)$ is to be continuously rectified at $101\mathrm{.}325$ kPa at a rate of$5000$ kg$/$h to provide a distillate containing $95\%$ methanol and a residue containing$1\mathrm{.}0\%$ nethanol $($by weight$).$ Calculate the flow rates of the distillate and residue on$($i$)$ weight basis and $($ii$)$ mole basis.Solution : Basis : $($i$)5000$ kg$/$h of methanol$-$water solution.Let x$,$ x$,$ and x$,$w be the weight fractions ot methanol in the teed, d$$st$$llate and residuerespectively. Let F$,$ D$\text{'}$ and W$"$ be the kg$/$h of the feed, distillate and residue, respectively.Overall material balance :F $=$ D$\text{'}+$ W$\text{'}5000=$ D$\text{'}+$ W$"$W$\text{'}=5000-$ D$\text{'}$