Instructions: Put your name, social security number, and section number on the top of this exam page.
Answer the following five (5) parts in the notation and conventions of the lecture for a total of 100 points.
Read the entire exam. Work alone and consult no one, living or dead, about this test (except Brucat) until
after you leave the room. Notebooks, textbooks and any other study material is not allowed in the exam
room. You may use only your own writing and calculating instruments (do not share). Show work where
appropriate and write only on this exam page. Show proper units to receive credit.
R = 0.08206 latm/molK = 8.314 J/Kmol = Universal Gas constant
Part I A gas sample is sealed in a vessel of fixed volume. The pressure of the gas in atmospheres is determined accurately at several temperatures. The temperatures are measured with a new thermometer which reads out in a new unit of temperature called the "degree Gator" or oG. Using the following table of data only, predict the value of the absolute zero of temperature on the Gator temperature scale.
|
Temperature |
Gas pressure |
| 25 oG | 1.35 atm |
| 50 oG | 1.55 atm |
| 100 oG | 1.95 atm |
Absolute Zero = -144 oG (-143.75)
|
Temperature |
Gas pressure |
| 15 oG | 2.10 atm |
| 35 oG | 2.25 atm |
| 75 oG | 2.55 atm |
Absolute Zero = -265 oG
|
Temperature |
Gas pressure |
| 125 oG | 1.35 atm |
| 150 oG | 1.55 atm |
| 200 oG | 1.95 atm |
Absolute Zero = -44 oG (- 43.75)
|
Temperature |
Gas pressure |
| 55 oG | 1.35 atm |
| 80 oG | 1.55 atm |
| 105 oG | 1.75 atm |
Absolute Zero = -114 oG (-113.75)
.
|
Temperature |
Gas pressure |
| 12 oG | 1.35 atm |
| 24 oG | 1.55 atm |
| 48 oG | 1.95 atm |
Absolute Zero = -69 oG
Part II The van der Waals Equation is the equation of state for a non-ideal gas. The properties of a gas predicted by this equation are different from that of an ideal gas.
(a) Under what two conditions are the properties of a real gas expected to be the most
non-ideal?
Low Temperature and High Pressure
ideal?
High Temperature and Low Pressure
(b) Calculate the pressure of a 0.100 mole of H2 at 25.0 K in a 100.0 mL vessel with the van der Waals equation of state assuming a= 0.244 L2 atm/mol2 and b = 26.6 mL/mol for this gas.
p = 1.86 atm
Calculate the pressure of a 0.250 mole of He at 10.5 K in a 100 mL vessel with the van der Waals equation of state assuming a= 0.0341 L2 atm/mol2 and b = 23.7 mL/mol for this gas.
p = 2.08 atm
Calculate the pressure of a 0.200 mole of O2 at 95.0 K in a 200 mL vessel with the van der Waals equation of state assuming a= 1.36 L2 atm/mol2 and b = 31.8 mL/mol for this gas.
p = 6.69 atm
Calculate the pressure of a 0.100 mole of H2O at 275.0 K in a 0.150 L vessel with the van der Waals equation of state assuming a= 5.46 L2 atm/mol2 and b = 30.5 mL/mol for this gas.
p = 12.9 atm
Calculate the pressure of a 0.100 mole of CCl4 at 350.0 K in a 1.10 L vessel with the van der Waals equation of state assuming a= 20.4 L2 atm/mol2 and b = 138.3 mL/mol for this gas.
p = 2.48 atm
Part III
(a) Calculate the temperature at which a mole of H2 [He, O2, H2O, CCl4] gas has 10.0 kJ of kinetic energy in the molecular motion of the gas.
T= 802 K
(b) What is the RMS speed of the molecules in meters per second at this temperature? (The molecular weight of H2 [He, O2, H2O, CCl4] is 2.016 [4.003, 32.00, 18.016, 153.84] g/mol)
uH2 = 3150 m/s
uHe = 2235 m/s
uO2 = 791 m/s
uH2O = 1054 m/s
uCCl4 = 361 m/s
Part IV The normal boiling point of C2H5OH is 352 K. The heat of condensation of C2H5OH is -35.27 kJ/mole. What is the vapor pressure of C2H5OH at 23 oC?
p = 0.102 atm
The normal boiling point of CCl4 is 350 K. The heat of condensation of CCl4 is -30.0 kJ/mole. What is the vapor pressure of CCl4 at 22 oC?
p = 0.146 atm
The normal boiling point of C6H6 is 353 K. The heat of condensation of C6H6 is -30.8 kJ/mole. What is the vapor pressure of C6H6 at 21 oC?
p = 0.122 atm
The normal boiling point of CH3OH is 337 K. The heat of condensation of CH3OH is -35.27 kJ/mole. What is the vapor pressure of CH3OH at 20 oC?
p = 0.151 atm
The normal boiling point of H2O is 373 K. The heat of condensation of H2O is -40.7 kJ/mole. What is the vapor pressure of H2O at 57 oC?
p = 0.181 atm
Part V Draw the phase diagram for pure water. Label the axes and regions in which only a pure
phase exists. Label the critical point and the triple point.
Point A is the Triple Point.
Point D is the Critical Point
On my Honor, I have neither given nor received unauthorized aid in the completion of this exam