$9\mathrm{.}9$ An open kettle contains $50$kmol of a dilute aqueous solution of methanol, mole fraction

methanol $=0\mathrm{.}02,$ at the bubble point, into which steam is continuously sparged. The entering steam

agitates the kettle contents so that they are always of uniform composition, and the vapor produced,

always in equilibrium with the liquid, is led away. Operation is adiabatic. For the concentrations

encountered it may be assumed that the enthalpy of the steam and evolved vapor are the same, the

enthalpy of the liquid in the kettle is essentially constant, and the relative volatility is constant at $7\mathrm{.}6.$

Compute the quantity of steam to be introduced in order to reduce the concentration of methanol in

the kettle contents to $0\mathrm{.}001$ mole fraction.

Ans.: $20\mathrm{.}5$kmol.