A system comprised of chloroform. 1,4-dioxane, and enthanol exists as a two-phase vapor/liquid system at 50 degree and 55 kPa. It is found, after the addition of some pure ethanol, that the system can be returned to two-phase equilibrium at the initial T and P. In what respect has the system changed, and in what respect has it not changed? For the system described in Pb 2.9: How many phase-rule variables in addition to T and P must be chosen so as to fix the compositions of both phases? If the temperature and pressure are to remain the same, can the overall composition of the system be changed (by adding or removing material) without affecting the compositions of the liquid and vapor phases? A tank containing 20 kg of water at 20 degree is fitted with a stirrer that delivers work the water at the rate of 0.25 kW. How long does it take for the temperature of the rise to 30 degree if no heat is lost from the water? For water, Cp = 4.18 kJ kg-1