$2-17.$ Determine the compositions and quantities of gas and liquid when$1$ lb mole of a mixture of $60$ mole percent methane and $40$ mole$2-18.$ Determine the composito can thanies of a sin Hiquid when$1$ lb mole of a mixture of $40$ mole percent methane and $60$ mole percent ethane is brought to equilibrium at $500$ psia and $-40\backslash$deg F$.$Compare your answer with the answer to problem $2-17.$ What was the effect of changing the composition of the mixture?