Unit 4 Test Flashcards
intermolecular forces
the attractive forces that exist among the particles that compose matter
dispersion force (London dispersion forces or Van der Waals forces)
An intermolecular force (also referred to as London force) exhibited by all atoms and molecules that results from fluctuations in the electron distribution
dipole–dipole force
An intermolecular force exhibited by polar molecules that results from the uneven charge distribution
How do you determine if a molecule has dipole-dipole forces?
(1) determine if the molecule contains polar bonds; and (2) determine if the polar bonds add together to form a net dipole moment
hydrogen bond
A strong attraction between the H atom on one molecule and the F, O, or N on its neighbor
ion–dipole force
An intermolecular force that occurs when an ionic compound is mixed with a polar compound
Rank the weakest to strongest intermolecular forces:
Dispersion, dipole-dipole, hydrogen bonding, ion-dipole bonding
How do you determine if a covalent bond has hydrogen bonding?
(1) draw the molecule (2) check to see if hydrogen is directly bonded with oxygen, fluorine, or nitrogen
How do you determine if a covalent bond has ion-dipole bonding?
(1) draw molecule (2) observe formal charges of atoms (3) check for polar charges (4) if an ionic compounds and polar compounds are present then there is a ion-dipole bonding
How do you predict boiling point trends and solubility trends based on intermolecular forces for given covalent compounds?
(1) compare intermolecular forces, the stronger the force, the higher the boiling point (2) if the intermolecular forces are the same, compare the molecular mass; the higher the molecular mass, the higher the boiling point
What type of intermolecular force is responsible for the solubility of ionic compounds?
Ion-dipole
surface tension
The energy required to increase the surface area of a liquid by a unit amount; responsible for the tendency of liquids to minimize their surface area, giving rise to a membrane-like surface
Surface tension decreases as intermolecular forces …
decreases
viscosity
A measure of the resistance of a liquid to flow
Viscosity increases as intermolecular forces …
increase
As temperature rises, viscosity…
decreases
As temperature rises, surface tension …
decreases
Rank the intermolecular forces from highest surface tension and viscosity to lowest:
ion-dipole
hydrogen bonding
dipole-dipole
dispersion forces
vaporization
the phase transition from liquid to gas
condensation
the phase transition from gas to liquid
sublimation
the transition phase from solid to gas
deposition
the transition phase from gas to solid
melting or fusion
the transition phase from solid to liquid
freezing
the transition phase from liquid to solid
The rate of vaporization … with increasing temperature.
increases
The rate of vaporization … with increasing surface area.
increases
The rate of vaporization … with decreasing strength of intermolecular forces.
increases
Endothermic or exothermic: vaporization
endothermic
Endothermic or exothermic: condensation
exothermic
Endothermic or exothermic: sublimation
endothermic
Endothermic or exothermic: deposition
exothermic
Endothermic or exothermic: fusion
endothermic
Endothermic or exothermic: freezing
exothermic
heat (or enthalpy) of vaporization (ΔHvap)
The amount of heat required to vaporize 1 mol of a liquid to a gas
heat (or enthalpy) of sublimation (ΔHsub)
The amount of heat required to sublime 1 mol of a solid to a gas
heat of fusion (ΔHfus)
The amount of heat required to melt 1 mol of a solid
heat (or enthalpy) of sublimation (ΔHsub)
The amount of heat required to sublime 1 mol of a solid to a gas
The sign of heat of vaporization is …
positive because it is an endothermic reaction
vapor pressure
The partial pressure of a vapor in dynamic equilibrium with its liquid
The stronger the intermolecular forces, the … the vapor pressure
lower
Formula for heat of sublimation:
heat of sublimination = heat of fusion + heat of vaporization
Formula for energy of ice warming:
q = m * C(ice) * delta(T)
Formula for energy of melting point:
q = n * delta(H_fusion)
n = number of moles (mol)
delta(H_fusion) = kJ/mol
Formula for energy of liquid water warming:
q = m * C_water * delta(T)
Formula for energy of boiling point:
q = n * delta(H_vaporization)
Formula for energy of steam warming:
q = m * C_steam * delta(T)
boiling point of a liquid
the temperature at which the pressure of the liquid’s vapor equals the pressure of its surroundings
normal boiling point of a liquid
the temperature at which its vapor pressure equals the standard atmospheric pressure at sea level, which is 760 millimeters of mercury or one atmosphere
draw and label the typical phase diagram using the following: solid, liquid, gas, sublimation curve, vaporization curve, fusion curve, triple point, critical point, supercritical fluid
compare with notes
triple point
The unique set of conditions at which all three phases of a substance are equally stable and in equilibrium
critical point
The temperature and pressure above which a supercritical fluid exists