Chapter 11 Liquids, Solids & Intermolecular Forces Flashcards
What are the 3 phases?
Solid, liquid & gas
Which of the following is not true about the solid phase? A) High density B) Limited to freedom of motion C) Weak intermolecular forces D) Short distance between molecules
C ; strong intermolecular forces
Which of the following is not true about the liquid phase?
A) Low density
B) Some freedom of motion
C) Moderate intermolecular forces
D) Somewhat short distance between molecules
A ; high density
Which of the following is not true about the gas phase? A) Low density B) Large freedom of motion C) Strong intermolecular forces D) Long distance between molecules
C ; weak intermolecular forces
T/F High degree of freedom = more unstable
True
T/F Low degree of freedom = neither stable/unstable
False ; more stable
What type of molecules are not easily compressible?
Molecules closely spaced
What type of molecules are highly compressible?
Molecules widely spaced
Define Thermal Expansion
The tendency of matter to change shape, area and volume in response to change in temperature
Does the solid phase have weak/moderate/strong Thermal Expansion?
Weak
Does the liquid phase have weak/moderate/strong Thermal Expansion
Moderate
Does the gas phase have weak/moderate/strong Thermal Expansion?
Strong
What is the process from solid to liquid phase?
Melting
What is the process from liquid to gas phase?
Vaporization
What is the process from gas to liquid phase?
Condensation
What is the process from liquid to solid phase?
Freezing
Define Intermolecular Forces?
Forces that hold condensed states together
The __________ of particles determines the __________ of Intermolecular Forces that hold the substance together
Structure ; strength
What is the equation for Coulomb’s Law?
E = 1 / 4(pi)E0 (q1q2 / r)
What does Coulomb’s Law state?
States that Intermolecular Forces are due to attractive forces between opposite charges
List the following Intermolecular Forces in order from weakest to strongest
London Dispersion
Dipole - Dipole
Hydrogen Bonding
Ion - Dipole
Which Intermolecular Force exists among all particles and molecules
London Dispersion Force
Define London Dispersion Force
When there are fluctuations in electron distributions within molecules or atoms
Define Polarizability
The ease with which the electron distribution around an atom or molecule can be distorted
Strong force = ________ polarized, ________ mass and __________ boiling point
Easily ; larger ; larger
Weak force = ________ polarized, ________ mass and _________ boiling point
Not easily ; smaller ; smaller
If a particle has the same mass what factor can be used to determine a difference in force?
Shape
Which halogen has the highest boiling point? F2, Cl2, Br2, I2
I2 ; because it has the largest mass
Define Dipole - Dipole Force
Force that is present between polar molecules
More polar = ________ dipole, _________ melting/boiling point
Stronger ; higher
Less polar = ________ dipole, __________ melting/boiling point
Weaker ; lower
Define Miscibility
The ability to mix without separating into 2 states
The _________ of a molecule affects the Miscibility
Polarity
Which has the higher melting/boiling point?
A) CH2O
B) C2H6
CH2O ; because it is more polar, which automatically means that it has a higher melting/boiling point
Which molecules have Dipole - Dipole Forces?
A) CO2
B) CH2Cl2
C) CH4
A and B
Define Hydrogen Bonding
Intermolecular forces that occur when polar molecules with H atoms are bonded directly to small/highly electronegative F, O and N atoms
T/F Hydrogen Bonding pairs include H-O, H-N and H-F
True
Define Ion Dipole Force
When ions from an ionic compound is mixed with a polar compound
Which Intermolecular Force is the strongest?
Ion Dipole Force
Determine what Intermolecular Force PH3 has
Dispersion, Dipole - Dipole
Determine what Intermolecular Force HBr has
Dispersion, Dipole - Dipole
Determine what Intermolecular Force CH3OH has
Dispersion, Dipole - Dipole, Hydrogen Bonding
Determine what Intermolecular Force He2 has
Dispersion
Arrange the following in order of increasing boiling point A) CH4 B) CH3CH3 C) CH3CH2Cl D) CH3CH2OH
A –> B –> C –> D
What are the Intermolecular Forces in action in liquids?
Tension, Viscosity and Capillary Action
Define Surface Tension
When a molecule on the interior can experience more Intermolecular Forces than a molecule on the surface
T/F Interior molecules are less stable
False; more stable
Surface tension _________ when Intermolecular Force __________
Decreases ; decreases
Define Viscosity
The resistance of a liquid to flow
Intermolecular Force _________ when viscosity ___________
Increases ; increases
Do longer molecules have higher or lower viscosity?
Higher
Higher temperature results in __________ viscosity
Lower
Why do longer molecules have higher viscosity?
Because think of a long rope, because it is so long it is likely to get tangled and jumbled, making it more difficult to move through
What is a good example of viscosity?
Honey (syrup)
Define Capillary Action
The ability of a liquid to flow against gravity up a narrow tube
What 2 actions work together to create capillary action?
Cohesive and adhesive forces
What does cohesive forces hold together?
Liquid molecules
What does adhesive forces hold together?
Outer liquid molecules to the tube’s surface
What is the liquid to gas phase called? What kind of process is occurring during this phase?
Vaporization ; endothermic (heat absorbed)
Define Heat of Vaporization
Amount of heat (enthalpy) required to vaporize 1 mole liquid to gas
T/F Heat of Vaporization will always be a positive value
True
What is the gas to liquid phase called? What kind of process is occurring during this phase?
Condensation ; exothermic (heat released)
Define Dynamic Equilibrium
When 2 opposite processes reach the same rate so there is no gain or loss of material
Weaker Intermolecular Forces results in _________ vapor pressure
Higher
Higher temperature results in __________ vapor pressure
Higher
T/F The stronger the Intermolecular Force the lower the boiling point
False ; higher
Pick the higher vapor pressure compound from each pair
A) Br2 or I2
B) CH4 or CH3Cl
C) NH3 or PH3
A) Br2
B) CH4
C) PH3
Place the following substances in order of increasing vapor pressure
A) NF3
B) NH3
C) BCl3
NH3 –> NF3 –> BCl3
Arrange the following compounds in order of increasing boiling points A) CH4 B) CH3CH3 C) CH3CH2Cl D) CH3CH2OH
A) Dispersion
B) Dispersion w/ larger mass
C) Dispersion, Dipole -Dipole
D) Dispersion, Dipole - Dipole, Hydrogen Bonding
What does the Clausius - Clapeyron equation state?
States that vapor pressure of a liquid increases with increasing temperature
Define Sublimation
The amount of heat required to sublime 1 mole of a solid to gas
Define Fusion
Phase transition from solid to liquid
Define Freezing
Phase transition from liquid to solid
T/F Heat of Fusion values are always negative
False ; positive
Define Phase Diagram
A map of the states of a substance as a function of pressure (y-axis) and temperature (x-axis)
What are the 3 main regions of Phase Diagrams?
Solid, liquid and gas
What do the regions of a Phase Diagram represent?
Represent the conditions where that particular state is stable
What do lines in Phase Diagrams represent?
Represent the substance when it is in equilibrium between the 2 states on either side of the line
T/F If a point lands on the line than it is coexisting between 2 states
True
What does Triple Point represent?
When the 3 states are equally states (coexist) and are in equilibrium
Define Supercritical Fluid
When the temperature and pressure in a Phase Diagram is ABOVE its critical point
T/F Liquid and gas states still exist in the supercritical fluid point
False ; do not exist
What is the equation for Clausius Clapeyron?
ln P2/P1 = -DeltaHvap / R (1/T2 - 1/T1)