1.
Chapt. 11 Practice Test
What is polarizability? The ease with which electron density can be distorted
2. What force(s) of attraction exist between He atoms? Dispersion forces
3. What type of substance would exhibit both dispersion forces and dipole-dipole forces? A polar substance
4. What type of force exists between a Ca2+ ion and water? Ion – dipole
5. True or False: PH3 is capable of hydrogen bonding false
6. List the properties of molecular compounds Soft, low melting point, poor conductor
7. List the properties of ionic compounds
Hard, brittle, high melting point, solid form is a poor conductor, aqueous or molten forms will conduct
8. Which of the following substances should have the highest boiling point? D
A. CH4
B. Cl2
C. Kr
D. CH3Cl
E. N2
9. What is the relationship between strength of intermolecular force and
a. Heat of vaporization stronger forces = greater heat of vaporization
b. Vapor pressure stronger forces = lower vapor pressure
c. Boiling point stronger forces = higher boiling point
d. Viscosity stronger forces = greater viscosity
10. Which of the following would have the lowest vapor pressure? C, it is capable of forming the most hydrogen
bonds
A.CH3OCH3
B. C2H5OH
C. HOCH2CH2OH
11. Each of the following substances is a liquid at 50C. Place these liquids in order of increasing vapor pressure.
dimethyl ether (CH3OCH3), propane (C3H8), ethanol (CH3CH2OH) Answer: B
A. ethanol < propane < dimethyl ether
B. ethanol < dimethyl ether < propane
C. propane < dimethyl ether < ethanol
D. dimethyl ether < ethanol < propane
E. propane < ethanol < dimethyl ether
12. Which one of the following substances should exhibit hydrogen bonding in the liquid state? Answer: E
A. PH3
B. He
C. H2S
D. CH4
E. CH3OH
13. What is surface tension? Give specific examples.
The amount of energy required to stretch or increase the surface of a liquid by a unit area.
Examples: Bug “walking” on water; pin floating on water
14. Which substance has the highest normal boiling point? D; it can hydrogen bond
a. CH3Cl
b. CH3Br
c. CH3I
d. CH3OH
15. When does a liquid boil?
When its vapor pressure reaches or exceeds the external pressure
16. Water boils at 71˚C on top of Mt. Everest (8848 m above sea level) and at 86˚C on top of Mt. Whitney (4418 m
above sea level). Why does water boil at a higher temperature on Mt. Whitney than on Mt. Everest?
At higher altitudes, atmospheric pressure is less than at lower altitudes. Boiling occurs when the vapor pressure of the
liquid equals the surrounding atmospheric pressure. Thus, water has a lower vapor pressure and boiling point on Mt.
Everest than on Mt. Whitney
17. List all the different phase changes that can occur and determine whether they are endothermic or exothermic.
Melting = endothermic
Freezing = exothermic
Vaporization = endothermic
Condensation = exothermic
Sublimation = endothermic
Deposition = exothermic
18. List ALL the types of intermolecular forces that exist between HCl and ICl. Dipersion and dipole-dipole
19. List ALL the intermolecular forces that exist between HF and H2O. Dispersion, dipole-dipole, and hydrogen
bonding
20. The specific heat capacity of liquid water is 4.184 J/g·C and the molar heat of vaporization is 40.7 kJ/mol. How
many kilojoules of heat must be provided to convert 2.50 g of liquid water at 45C into 2.50 g of steam at 100C?
1. Step One: Heat the water to 100.0°C
q= Cm∆T
q= 575.3 J
2. Convert liquid to steam
a. First change grams to moles (0.139 mol)
b. Multiply the molar heat of vaporization (5.65 kJ)
3. Add steps 1 and 2 together (make sure they are in the same units): = 6.23 kJ
21. Calculate the amount of heat needed to melt 1.25 kg of iron at its melting point (1,809 K), given that: Hfus = 13.80
kJ/mol.
Convert kg to grams and then to moles
Multiply by the molar heat of fusion
Answer = 308.9 kJ
22.
Explain why water forms a meniscus in a capillary tube.
The water adheres to the wall of the glass tube. These adhesive forces are stronger than the cohesive forces, causing
water to rise up the glass tube.
D
C
B
A
23. What is the normal boiling point of the substance with the phase diagram shown above? 400˚C
24. What is the temperature and pressure at the triple point? 100˚C, 0.65 atm
25. Which segment corresponds to the conditions of temperature and pressure under which the solid and liquid are in
equilibrium? BD
26. Which letter corresponds to the critical point? What type of substance exists past the critical point? C; supercritical
fluid
27. If I had a quantity of this substance at a pressure of 1.25 atm and a temperature of 300 0 C and lowered the
pressure to 0.25 atm, what phase transition(s) would occur? vaporization
28. What state of matter is this substance in at 300˚C and 1.50 atm? liquid