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Question 1

What are intermolecular forces?

Answer 1

electrostatic forces that exist among particles, the state of matter depends on the magnitude of IMF and thermal energy

Question 2

What are the characteristics of gas

Answer 2

low density, no definite shape, no definite volume, weak intermolecular forces

Question 3

What is the major difference between liquid and solid states

Answer 3

The thermal energy.

liquid states have enough thermal energy to overcome IMF and can move around each other

Solid states have atoms/molecules locked in place and can only vibrate back and forth in their fixed positions

Question 4

At room temperature and pressure, medium to strong IMF’s result in:

Answer 4

liquid or solid states with a high boiling/melting point

Question 5

At room temperature and pressure, weak IMF’s result in:

Answer 5

gas states with low melting/boiling points

Question 6

IMFS can result from

Answer 6

full charges, dipoles, and/or temporary charges

Question 7

The energy of a compound becomes _______ as oppositely chatged species _______ in magnitude or ______ in distance

Answer 7

more exothermic, increase, come closer

Question 8

Difference between intermolecular and intramolecular forces

Answer 8

‘Intra’ means within, so intramolecular forces occur within a molecule. ‘Inter’ means between, so intermolecular forces occur between molecules

Question 9

What are the main types of IMF in order of strongest to weakest

Answer 9

Ion dipole, Hydrogen bonding, Dipole-Dipole, London Disperson forces

Question 10

What are London dispersion force characteristics?

Answer 10

present in all molecules
-result from fluctuations in e- distributions, resulting in an instantaneous dipole

Question 11

What do instantaneous dipoles do to neighboring molecules

Answer 11

They create temporary dipoles in them

Question 12

What is polarizability and how does it relate to LDF’s

Answer 12

Polarizability is how easily an electron can move, the magnitude of LDF’s depends on the atoms/molecules

Question 13

What are some characteristics related to the polarizability

Answer 13

Larger molecules/atoms are more polarizable due to their larger electron cloud

a larger electron cloud allows for a stronger LDF since the electron is held less tightly by the nucleus

Question 14

How is molar mass and surface area related to LDF’s?

Answer 14

Larger molar masses create a higher LDF since the electrons are dispersed over a greater area

Shape dictates the overall surface area where LDF can occur

Question 15

How can you predict higher LDFs (and therefore higher boiling points)

Answer 15

first, compare the molar masses
if the molar masses are similar then consider the shape

Question 16

What are some characteristics of Dipole-Dipole Forces?

Answer 16

-they are present in all polar molecules (molecules that have regions of partial negative and partial positives, creating permanent dipoles)

-compounds with LDF and dip-dip have higher melting/boiling points than compounds with just LDF’s

Question 17

What is true about dipole moments and molar masses?

Answer 17

if the molar masses are similar, then the compound with the greater dipole moment will have a higher boiling point

Question 18

What is hydrogen bonding?

Answer 18

a special kind of dip-dip force
-only occur in polar molecules that contain H-F, H-O, and H-N bonds
-only occur between a H bonded to F,O,N and the F,O,N on the neighboring molecule

Question 19

Why do hydrogen bonds occur with F,O,N

Answer 19

F,O, N are small and highly electronegative. these small sizes allow for closer interactions

Question 20

What is Ion-Dipole Forces

Answer 20

occur when a soluble ionic compound is mixed with a polar compound

Question 21

How is the rate of vaporization related to temperature, surface area, and IMF

Answer 21

Higher temps, higher surface area=higher rate of vaporization

weaker IMF=higher rate of vaporization

Question 22

What is vapor pressure

Answer 22

The pressure of a gas in dynamic equilibrium with its liquid

Weak intermolecular forces result in highly volatile substances with high vapor pressures

Strong intermolecular substances result in non volatile substances with low vapor pre

Question 23

what is sublimation

Answer 23

when a solid becomes a gas without becoming a liquid first

Question 24

what is deposition

Answer 24

when a gas becomes a solid without becoming a liquid first

Question 25

what is fusion

Answer 25

it is the transition of a solid to a liquid (melting) it is an endothermic process since solid is higher energy

Question 26

as intermolecular forces increase what happens to boiling point

Answer 26

it increases

Question 27

how are surface tension and intermolecular forces related

Answer 27

as surface tension increases, the IMF increases

Question 28

how is viscosity (thickness of solution) related to IMF

Answer 28

As the IMFs increase the viscosity increases since the molecules are more attracted to eachother and do not move around eachother as much

Question 29

increases in pressure favor what states of matter?

Answer 29

Denser states

Question 30

what is surface tension

Answer 30

the tendency of liquid to minimize surface area by creating a skin

surface tension decreases with decreasing intermolecular forces

Question 31

what is viscosity

Answer 31

the resistance of liquid to flow

Question 32

what are adhesive forces and what is their relationship to cohesive forces

Answer 32

the attraction between liquid molecules and tube surfaces

if the adhesive forces are stronger than the cohesive forces then the liquid will climb up the tube surface until gravity forces a balance with the adhesive forces

Question 32

what are cohesive forces

Answer 32

the attraction between liquid molecules

Question 33

what is vaporization

Answer 33

the transition of a liquid to a gas when enough energy has been put into a liquid to overcome the IMF’s

Question 34

how is vaporization related to temperature, surface area, and intermolecular forces

Answer 34

the rate of vaporization increases with increased temperature and surface area and with weak IMFS

Question 35

what is the heat of vaporization?

Answer 35

the amount of heat required to vaporize 1 mol of liquid into a gas