Exam 1
The molar heats of sublimation and fusion of iodine are 62.3 kJ/mol and 15.3 kJ/mol,respectively. Calculate the molar heat of vaporization of liquid iodine.
47 kJ/mol DHfusion + DHvaporization = DHsublimation DHvaporization = DH sublimation - DHfusion DHvap= 62.3-15.3
how many basic unit cells are there?
7
Which of the following properties indicates the presence of strong intermolecular forces in a liquid? A)a low vapor pressure B)a low critical temperature C)None of the above. D)a low heat of vaporization E)a low boiling point
A
Which of the following characteristics indicates the presence of weak intermolecular forces in a liquid? A) a high boiling point B) a low heat of vaporization C) None of the above. D) a low vapor pressure E) a high critical temperature
B
Which of the following is expected to have the highest normal boiling point? H2 Br2 O2 N2 F2
Br2 because it is the largest
Butter melts over a range of temperatures, rather than with a sharp melting point. Butter is classified as a/an A)covalent solid. B)ionic crystal. C)amorphous solid. D)metallic crystal. E)molecular crystal.
C
Charcoal is classified as a/an A)ionic crystal. B)metallic crystal. C)molecular crystal. D)amorphous solid. E)covalent solid.
C
which of the following is expected to have the highest normal boiling point? C2H6 C3H8 C5H12 C4H10 CH4
C5H12 -> it's the largest molecule
Which of the following is expected to have the lowest normal boiling point? C2H6 C3H8 C5H12 C4H10 CH4
CH4 -> the smallest molecule
Which substance would have the smallest molar heat of vaporization? C4H10 C5H12 C3H8 CH4 C2H6
CH4 is the smallest -> weaker intermolecular force
What type(s) of intermolecular forces exist between the following pairs? HBr and H2S
Dipole-Dipole
Which pure substance would have the largest molar heat of vaporization? Ar H2 N2 H2O CH4
H2O has hydrogen bonding -> stronger intermolecular force
Which of the following is expected to have the highest normal boiling point? HF HCl HBr HI HAt
HF -> Florine is the most electronegative -> strongest intermolecular forces
molecular crystal
Held together by H-bonding, dipole-dipole dispersion forces Low melting point Soft No conductivity
The intermolecular forces present in CH3CH2NH2 include which of the following? I. dipole-dipole II. ion-dipole III. dispersion IV. hydrogen bonding
I., III., IV.
an example of a covalent network solid is:
a diamond
hydrogen bonding
a special dipole-dipole interaction between hydrogen atoms in polar N-H, O-H, F-H bonds AND have a lone pair on the N, O, or F
dipole-dipole forces
attractions between oppositely charged regions of polar molecules
ion-induced dipole
cation or anion causes a neutral atom (non-polar) to become temporarily polar by unevenly distributing the electrons within the cloud
does viscosity increase or decrease with increasing temperature?
decreases
The solubility of gases in water usually increases with
decreasing temperature and increasing pressure
Soot collecting on the inside of a chimney is an example of which phase transition?
deposition gas -> solid
What type(s) of intermolecular forces exist between the following pairs? NH3 and C6H6
dipole-induced dipole
boiling point elevation and vapor pressure lowering are _______ proportional to the molal concentration of solute species:
directly
freezing point depression and molality are ____ proportional
directly
electronic geometry vs molecular geometry
electronic geometry describes the spatial arrangement of all pairs of electrons around the central atom, both bonding and lone pairs molecular geometry describes the spatial arrangement of only the bonding pairs of electrons ex. NH3 electronic G= tetrahedral molecular G= trigonal pyramidal
Which phase changes are exothermic?
freezing, condensation, deposition
Rank the states of matter from weakest to strongest intermolecular forces.
gas < liquid < solid
deposition
gas to solid
greater intermolecular forces = ______ boiling point
greater
if there is a positive slope, the density of the state on the left will be _____ than the state on the right
greater ex: solid carbon is more dense than liquid carbon
if there is a negative slope, the density of the state on the right will be _____ than the state on the left
greater ex: water is more dense than ice
covalent solids
high melting point hard poor conductor of heat and electricity
ionic solids
high melting point hard but brittle as a solid is a poor conductor of heat and electricity as a liquid is a good conductor of electricity
the larger the molecule, the ________ it's viscosity
higher
the lower the freezing point, the _____ the delta T (change in freezing/melting point)
higher
What type(s) of intermolecular forces exist between the following pairs? Cl2 and HBr4
instantaneous dipole-induced dipole
ion-dipole forces
ion bonding to polar molecules
What type(s) of intermolecular forces exist between the following pairs? I2 and NO3-
ion-induced dipole
what types of molecule experiences larger dispersion forces?
larger and heavier atoms and molecules exhibit stronger dispersion forces
the higher the molality, the _____ the freezing point
lower
adding a nonvolatile solute to a solution _____ the freezing point
lowers
adding a nonvolatile solute to a solvent
lowers the solutions vapor pressure making the water boil hotter
Which phase changes are endothermic?
melting, vaporization, sublimation
crystalline solid
particles are arranged in a definite repeating pattern
dipole-induced dipole
polar molecule when placed next to a non-polar molecule temporarily creates an induced charge within the non-polar molecule
What is the result of a force distributed over an area?
pressure
during osmosis, what passes through a membrane?
pure solvent
strong intermolecular forces = ______ vapor pressure
smaller
metallic crystals
soft or hard low or high melting point good conductor
sublimation
solid to gas
amorphous solid
solids that lack an ordered internal structure melts over a wide range of temperatures rather than a sharp melting point
strong or weak intermolecular forces have a greater sufrace tension?
strong
strong or weak intermolecular forces have a high boiling point?
strong
What factors affect the pressure of an enclosed gas?
temperature
what is viscoity?
the resistance of a liquid to flow greater resistance = greater viscosity
if there is a negative deviation to raoult's law, then:
the solvent-solute interaction is stronger than the solvent-solvent interaction and the solute-solute interaction
if there is a positive deviation to raoult's law then"
the solvent-solvent and solute-solute interaction are stronger than the solvent-solute interaction
in terms of x-ray diffraction patterns, what is the difference between a natural diamond and a man-made/synethetic one
there is no difference
instantaneous dipole-induced dipole
two non-polar molecules next to each other creates an instantaneous dipole in a molecule and can cascade down a system