chem121test6

Question 1

three states of matter

Answer 1

solid, liquid, and gas

Question 2

Intermolecular Forces

Answer 2

forces between molecules

Question 3

The fundamental difference between states of matter

Answer 3

is the strength of the intermolecular forces of attraction

Question 4

Stronger forces bring

Answer 4

molecules closer together

Question 5

average kinetic energy

Answer 5

related to temperature

Question 6

gas

Answer 6

kinetic energies > energies of attraction

Question 7

liquid

Answer 7

comparable energies and energies of attraction

Question 8

solid

Answer 8

energies of attraction > kinetic energies

Question 9

Solids and liquids are referred to as the

Answer 9

condensed phases

Question 10

Intermolecular attractions are

Answer 10

weaker than bonds

Question 11

Hydrogen bonds are

Answer 11

NOT chemical bonds.

Question 12

Weakest to strongest forces:

Answer 12

Dispersion forces
Dipole–dipole forces
Hydrogen bonding

Question 13

Dispersion Forces

Answer 13

the ability of a nonpolar atom to be temporarily polarized by the movement of its electron

Question 14

polarizability

Answer 14

The tendency of an electron cloud to distort

Question 15

Factors That Affect Amount of
Dispersion Force in a Molecule

Answer 15

Number of electrons in an atom (more electrons, more dispersion force)
Size of atom or molecule/molecular weight
Shape of molecules with similar masses (more compact, less dispersion force)

Question 16

If something is less polarizable

Answer 16

it has a lower boiling point

Question 17

Dipole–Dipole Interactions

Answer 17

the ability of polar molecules to attract their opposite ends to eachother

Question 18

the more polar the molecule

Answer 18

the higher its boiling point

Question 19

Which Have a Greater Effect:
Dipole–Dipole Interactions or
Dispersion Forces?

Answer 19

If two molecules are of comparable size and shape, dipole–dipole interactions will likely be the dominating force.
If one molecule is much larger than another, dispersion forces will likely determine its physical properties.

Question 20

Hydrogen Bonding

Answer 20

The dipole–dipole interactions experienced when H is
bonded to N, O, or F are unusually strong

Question 21

A hydrogen bond

Answer 21

is an attraction between a hydrogen atom attached to a highly electronegative atom and a nearby small electronegative atom in another molecule or chemical group

Question 22

Ice Compared to Liquid Water

Answer 22

Hydrogen bonding makes the molecules farther apart in ice than in liquid water

Question 23

Ion–Dipole Interactions

Answer 23

Ion–dipole interactions are found in solutions
of ions

Question 24

When two molecules have comparable molar masses and shapes

Answer 24

dispersion forces are roughly equal

Question 25

When two molecules have very different molar masses and there is no H-bonding

Answer 25

dispersion force determines the substance with stronger attractions

Question 26

Liquid Properties Affected by Intermolecular Forces

Answer 26

Boiling point (previously discussed) and melting point Viscosity Surface tension Capillary action

Question 27

viscosity

Answer 27

Resistance of a liquid to flow is called

Question 28

Viscosity increases

Answer 28

with stronger intermolecular forces

Question 29

viscosity decreases

Answer 29

with higher temperature

Question 30

Surface Tension

Answer 30

Water acts as if it has a “skin” on it due to extra inward forces on its surface. It causes water to “bead up” when in contact with nonpolar surfaces.

Question 31

cohesive forces

Answer 31

Intermolecular forces that bind similar molecules to one another are called

Question 32

adhesive forces

Answer 32

Intermolecular forces that bind a substance to a surface are called

Question 33

capillary action

Answer 33

The rise of liquids up narrow tubes

Question 34

cohesive

Answer 34

> adhesive

Question 35

phase change

Answer 35

Conversion from one state of matter to another is called a

Question 36

Phase changes:

Answer 36

melting/freezing, vaporizing/condensing, subliming/depositing

Question 37

heat of fusion

Answer 37

the energy required to change a solid at its melting point to a liquid

Question 38

heat of vaporization

Answer 38

the energy required to change a liquid at its boiling point to a gas

Question 39

heat of sublimation

Answer 39

the energy required to change a solid directly to a gas

Question 40

heating curve

Answer 40

A graph of temperature vs. heat added

Question 41

Vapor Pressure

Answer 41

At any temperature, some liquid molecules have enough energy to escape the surface and become a gas. As the temperature rises, the fraction of molecules that have enough energy to break free increases.

Question 42

boiling point of a liquid

Answer 42

the temperature at which its vapor pressure equals atmospheric pressure

Question 43

normal boiling point

Answer 43

the temperature at which a liquid's vapor pressure is 760 torr

Question 44

critical temperature

Answer 44

The temperature beyond which a gas cannot be compressed

Question 45

critical pressure

Answer 45

The pressure needed to compress the liquid at critical temperature

Question 46

supercritical fluid

Answer 46

The state beyond critical temperture and pressure

Question 47

phase diagram

Answer 47

a graph showing states of matter under conditions of temperature and pressure

Question 48

Unusual feature for water

Answer 48

The slope of the melting curve is negative (as the pressure is increased, the melting point decreases).

Question 49

Unusual features for carbon dioxide

Answer 49

Cannot exist in the liquid state at pressures below 5.11 atm (triple point). CO2 sublimes at normal pressures

Question 50

Liquid Crystals

Answer 50

Some substances do not go directly from the solid state to the liquid state. In this intermediate state, liquid crystals have some traits of solids and some of liquids. Molecules in liquid crystals have some degree of order

Question 51

nematic liquid crystals

Answer 51

molecules are ordered in only one dimension, along the long axis

Question 52

smectic liquid crystals

Answer 52

molecules are ordered in two dimensions, along the long axis and in layers

Question 53

cholesteric liquid crystals

Answer 53

nematic-like crystals are layered at angles to each other