Chem 125Dr. Retsek
- State the primary IMFs between the pairs of molecules/ions listed below.
Molecule/Ion Pairs / IMFs
NH3 and H2O
MgCl2 and H2O
N2 and H2
I2 and H2O
SO2 and SO2
- Circle all of the species below that can form a hydrogen bond. Explain why the other species couldn't hydrogen bond.
C2H6 CH3NH2 KCl CH3CH2CH2OH
- Which of the following species should have the weakest intermolecular forces? Why?
(rank from weakest to strongest)
CaCl2 I2 N2 H2O
- Which of the following materials should have the highest boiling point? Why?
(rank the boiling points from highest to lowest)
H2Se H2S H2Po H2Te
- Which of the following materials should be the most viscous? Why?
(rank from least viscous to most viscous)
H2O HOCH2CH2OH Br2 CH3(CH2)3CH3
- Which of the following substances should have the highest melting point? Why?
(rank the melting points from lowest to highest)
I2 Ag MgO NaI
- Which of the following substances should have the highest vapor pressure? Why?
(rank from highest to lowest vapor pressure)
CH4 CH3CH3 CH3CH2CH3
- Dichloromethane, CH2Cl2 (2 chlorines), is an organic solvent used for removing caffeine from coffee beans. The following table gives the vapor pressure of dichloromethane at various temperatures.
Temperature (°C) / Vapor Pressure (torr)
-10.0 / 80.1
0.0 / 133.6
10.0 / 213.3
20.0 / 329.6
30.0 / 495.4
40.0 / 724.4
Using the data above, generate the following two graphs (hint: watch the units on T!):
- Pvap vs. T
- ln Pvap vs. 1/T
Using the plots you made, answer the following questions:
(a)Choose any two temperatures and corresponding pressures in the table to calculate Hvap.
(b)Find the value (in kJ/mole) for Hvap for dichlormethane using only the plots or the equation of the line from the plots.
(c)How does the value you found from the graphs compare to the value from the data in the table?
Dichloromethane, CH2Cl2 (2 chlorines), is an organic solvent used for removing caffeine from coffee beans. The following table gives the vapor pressure of dichloromethane at various temperatures.
Temperature (°C) / Vapor Pressure (torr)-10.0 / 80.1
0.0 / 133.6
10.0 / 213.3
20.0 / 329.6
30.0 / 495.4
40.0 / 724.4
(d)At a temperature of 300 K and 300 torr are the liquid and gas at equilibrium? How can you tell? If the system is not at equilibrium, what would need to happen in order for the system to regain equilibrium?
(e)What would be the vapor pressure at 25.0°C?
Dichloromethane, CH2Cl2 (2 chlorines), is an organic solvent used for removing caffeine from coffee beans. The following table gives the vapor pressure of dichloromethane at various temperatures.
Temperature (°C) / Vapor Pressure (torr)-10.0 / 80.1
0.0 / 133.6
10.0 / 213.3
20.0 / 329.6
30.0 / 495.4
40.0 / 724.4
(f)Calculate the normal boiling point (in °C).
- Given the phase diagram below, answer the following questions.
(a)What phases exist at each point (A, B, C, D, and E) on the phase diagram above?
(b)Which point is the triple point? ______
(c)Which point is the critical point? ______
(d)If the current conditions are 25°C and 2000 torr, to what temperature would a sample have to be heated to produce liquid at 2000 torr?
(e)If the current conditions are 45°C and 500 torr, to what pressure would a sample have to be compressed to produce liquid at 45°C?