Chapt. 11 Practice Test
What is polarizability? The ease with which electron density can be distorted
What force(s) of attraction exist between He atoms? Dispersion forces
What type of substance would exhibit both dispersion forces and dipole-dipole forces? A polar substance
What type of force exists between a Ca2+ ion and water? Ion – dipole
True or False: PH3 is capable of hydrogen bonding false
List the properties of molecular compounds Soft, low melting point, poor conductor
List the properties of ionic compounds
Hard, brittle, high melting point, solid form is a poor conductor, aqueous or molten forms will conduct
Which of the following substances should have the highest boiling point? D
A. CH4 B. Cl2 C. Kr D. CH3Cl E. N2
What is the relationship between strength of intermolecular force and
Heat of vaporization stronger forces = greater heat of vaporization
Vapor pressure stronger forces = lower vapor pressure
Boiling point stronger forces = higher boiling point
Viscosity stronger forces = greater viscosity
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
Each of the following substances is a liquid at 50C. 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
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
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
Which substance has the highest normal boiling point? D; it can hydrogen bond
CH3Cl
CH3Br
CH3I
CH3OH
When does a liquid boil?
When its vapor pressure reaches or exceeds the external pressure
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
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
List ALL the types of intermolecular forces that exist between HCl and ICl. Dipersion and dipole-dipole
List ALL the intermolecular forces that exist between HF and H2O. Dispersion, dipole-dipole, and hydrogen bonding
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 45C into 2.50 g of steam at 100C?
Step One: Heat the water to 100.0°C
q= Cm∆T
q= 575.3 J
Convert liquid to steam
First change grams to moles (0.139 mol)
Multiply the molar heat of vaporization (5.65 kJ)
Add steps 1 and 2 together (make sure they are in the same units): = 6.23 kJ
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
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.
B C A D
What is the normal boiling point of the substance with the phase diagram shown above? 400˚C
What is the temperature and pressure at the triple point? 100˚C, 0.65 atm
Which segment corresponds to the conditions of temperature and pressure under which the solid and liquid are in equilibrium? BD
Which letter corresponds to the critical point? What type of substance exists past the critical point? C; supercritical fluid
If I had a quantity of this substance at a pressure of 1.25 atm and a temperature of 3000 C and lowered the pressure to 0.25 atm, what phase transition(s) would occur? vaporization
What state of matter is this substance in at 300˚C and 1.50 atm? liquid
CONFIGURING USER STATE MANAGEMENT FEATURES 73 CHAPTER 7 IMPLEMENTING
INTERPOLATION 41 CHAPTER 5 INTERPOLATION THIS CHAPTER SUMMARIZES POLYNOMIAL
PREPARING FOR PRODUCTION DEPLOYMENT 219 CHAPTER 4 DESIGNING A
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