Pretend you don’t know and can’t look up the vapor pressure of butane at 250 K. What are the solutions for V [m3/mol] from the van der Waals equation for n-butane at T = 250 K and P = 0.2 MPa. Give only the solutions that *could* represent stable equilibrium phases, based upon what you know.
A. (0.000 150, 0.000 549, 0.009 81)
B. (0.000 549)
C. (0.0176)
D. (0.000 150, 0.00981)
E. None of these are the real solutions
A. Incorrect. These are the solutions for V, but the middle one cannot be physically meaningful, regardless of the vapor pressure.
B. Incorrect. This is one of the values obtained from the correct calculation, but there are three solutions and this is the middle one, which is not physically meaningful.
C. Incorrect. You have confused temperature and critical temperature in your calculations. At these conditions the isotherm is subcritical.
D. Correct. Without knowing the vapor pressure, you cannot determine which of these two is a stable equilibrium phase. In Chapter 8 we will learn to estimate vapor pressure from an equation of state.
E. Incorrect. One of these is the correct answer.
You might also like to view...
Match the temperature in degrees Fahrenheit with the correct equivalent Celsius temperature.
A. 95°F B. 14°F C. 392°F D. 176°F E. 59°F F. 122°F
________ mites feed on the blood of pupae and adult bees
a. Tracheal c. Brood b. Apiary d. Varroa
Which of the following systems will require disabling the high voltage (HV) system during service?
A) Tire rotation B) Air filter replacement C) Electric AC compressor replacement D) Oil change
Typical maximum rotor runout specifications are ________
A) 0.300 to 0.500 in. (8.0 to 13 mm) B) 0.003 to 0.005 in. (0.08 to 0.13 mm) C) 0.0003 to 0.0005 in. (0.008 to 0.013 mm) D) 0.030 to 0.050 in. (0.8 to 1.3 mm)