Consider a 2-km-deep gas well containing a gas mixture of methane and ethane at a uniform temperature of 30◦C. The pressure at the top of the well is 14 MPa, and the composition on a mole basis is 90% methane, 10% ethane. Each component is in equilibrium (top to bottom), with d_G + g d_Z = 0, and assume ideal gas; so, for each component, Eq.14.10 applies. Determine the pressure and composition at the bottom of the well.