Ch 12: Liquids, Solids, and Intermolecular Forces Flashcards
What are intermolecular forces?
The attractive forces that exist among all the particles that compose matter.
A sphere is the geometric shape with the lowest _______ ____ to ______ ratio. This shape maximizes their interaction with one another (within the sphere) bc the sphere results in the minimum number of molecules being at the surface of the liquid where fewer interactions occur.
….surface area to volume ratio.
What is the molar volume?
The amount of volume occupied by 1 mole of a compound (or element) at a given temperature or pressure. It is given by the molar mass (or molecular weight) divided by the density of the compound/element.
https://www.sciencedirect.com/topics/chemistry/molar-volume
Don’t forget that water is atypical, in that its solid form is slightly ____ dense than its liquid form.
less
What is the strength of the intermolecular forces relative to thermal energy in each of the following states?
gas
liquid
solid
weak
moderate
strong
Propane exists as a gas at room temperature and atmospheric pressure, but it liquifies at pressures exceeding __ atm, which is why you can purchase it in liquid form in a tank.
2.7
Which is the strongest of the intermolecular forces?
ion-dipole forces are the strongest types of intermolecular forces
Which properties increase in magnitude with increasing strength of intermolecular forces? Check all that apply.
__viscosity
__surface tension
__vapor pressure
__boiling point
x viscosity
x surface tension
__vapor pressure
x boiling point
(all except vapor pressure)
In regard to vaporization and vapor pressure, what does the term dynamic equilibrium mean?
that the rate of evaporation = rate of condensation
What is vapor pressure?
The pressure of a gas in dynamic equilibrium with its liquid.
p. 516
Weak intermolecular forces result in volatile (easily vaporizable) substances with ___ vapor pressures bc the intermolecular forces are easily overcome by thermal energy.
high
p. 516
Strong intermolecular forces result in nonvolatile substances with {high or low} vapor pressures at a given temperature.
low
p. 516
What is the enthalpy of vaporization?
the heat required to vaporize one mole of a liquid to gas
The higher number of atoms in a molecule that can participate in hydrogen bonding, the _______ the intermolecular forces.
stronger
The boiling point of a liquid is the temperature at which the liquid’s _____ ________ equals the ________ _________.
vapor pressure
external pressure
p. 517
The approximate pressure at the summit of Mount Everest is only 0.32 atm, which makes the boiling point of water only __°C.
78°C
With how many other water molecules can a single molecule of water form hydrogen bonds?
4 other water molecules
p. 530
What features of water give it a relatively high boiling point?
Its bent geometry and the highly polar nature of the O-H bond results in a molecule with a significant dipole moment.
p. 530
Since boiling point increases with increasing strength of intermolecular forces, and since the halogens only have the __________ force (which increases with increasing molar mass), the boiling points of the halogens increase with increasing molar mass. Iodine has the highest molar mass of the halogens in this list, so it has the highest boiling point.
dispersion
Which property of a liquid increases with increasing temperature?
surface tension, viscosity, or vapor pressure
vapor pressure
What is the gas constant in J/mol K and kJ/mol K?
- 314 J/mol K
- 314 x 10-3 kJ/mol K
Phase changes
The process of transformation from a gas directly into the solid state is known as __________.
The opposite process – that is a solid changing into a gas – is known as __________.
deposition
sublimation
The transition from a solid to a liquid is known as melting or ______. The opposite of this process is ________, which changes a liquid into a solid. Thus, the freezing point = the ______ point.
fusion
freezing
fusion
What does the plateau region at 0°C of a melting/ freezing curve represent?
That a mixture of water and ice always has a temperature of 0°C (at 1 atm pressure).
The key concept is that once the melting point of a solid is reached, additional heating only causes more rapid melting. It does not raise the temperature of the solid above its melting point.
p. 524(?)