Chapter 12: Liquids & Solids

Question 1

Intermolecular forces

Answer 1

attractive forces that hold particles together in the condensed phases

Question 2

The magnitude (and type) of intermolecular forces is what determines…

Answer 2

Phase

Question 3

Surface tension

Answer 3

the amount of energy required to stretch or increase the surface of a liquid by a unit area

Question 4

The stronger the intermolecular forces, the ______ the surface tension.

Answer 4

higher

Question 5

Capillary action

Answer 5

the movement of a liquid up a narrow tube

Question 6

The two types of forces bring about capillary action

Answer 6

Cohesion & adhesion

Question 7

Cohesion

Answer 7

the attraction between like molecules

Question 8

Adhesion

Answer 8

the attraction between unlike molecules

Question 9

Viscosity

Answer 9

a measure of a fluid’s resistance to flow

Question 10

The higher the viscosity the more ____ a liquid flows

Answer 10

slowly

Question 11

Liquids that have higher intermolecular forces have _____ viscosities.

Answer 11

higher

Question 12

If a molecule at the surface of a liquid has enough kinetic energy, it can escape to the gas phase in a process called:

Answer 12

Vaporization

Question 13

The vapor pressure increases until

Answer 13

the rate of evaporation equals the rate of condensation.

Question 14

When the forward process and reverse process are occurring at the same rate, the system is in

Answer 14

dynamic equilibrium

Question 15

The vapor pressure increases with

Answer 15

Temperature

Question 16

The Clausius–Clapeyron equation relates

Answer 16

the natural log of vapor pressure and the reciprocal of absolute temperature

Question 17

Boiling point

Answer 17

the temperature at which the vapor pressure equals the external atmospheric pressure

Question 18

Boiling point varies with (2 things):

Answer 18

1. external pressure

2. the magnitude of intermolecular forces

Question 19

Melting Point

Answer 19

the temperature at which the energies of the individual particles enable them to break free of their fixed positions.

Question 20

Amorphous solids

Answer 20

lack a regular three-dimensional arrangement of atoms.

example: glass

Question 21

crystalline solid

Answer 21

possess rigid and long-range order; its atoms, molecules, or ions occupy specific positions.

Question 22

the basic repeating structural unit of a crystalline solid

Answer 22

unit cell

Question 23

coordination number

Answer 23

the number of atoms surrounding an atom in a crystal lattice; indicates how tightly the atoms are packed together

Question 24

The basic repeating unit in the array of atoms is called a

Answer 24

simple cubic cell

Question 25

body-centered cubic cell

Answer 25

the spheres in each layer rest in the depressions between spheres in the previous layer (CN=8)

Question 26

face-centered cubic cell (f c c), the coordination number is

Answer 26

12

Question 27

A simple cubic cell has the equivalent of

Answer 27

only one complete atom contained within the cell.

Question 28

A body-centered cubic cell has

Answer 28

two equivalent atoms

Question 29

A face-centered cubic cell contains

Answer 29

four complete atoms

Question 30

Ionic crystals

Answer 30

composed of charged ions that are held together by Coulombic attraction.

Question 31

The unit cell of an ionic compound can be defined by either:

Answer 31

the positions of the anions or the positions of the cations.

Question 32

In covalent crystals, atoms are held together in

Answer 32

an extensive three-dimensional network entirely by covalent bonds.

Question 33

In molecular crystals, the lattice points are occupied by ______; the attractive forces between them are __________ and/or __________.

Answer 33

molecules

van der Waals forces and/or hydrogen bonding

Question 34

metallic crystals

Answer 34

every lattice point is occupied by an atom of the same metal

Question 35

Large cohesive force resulting from _____ makes metals strong

Answer 35

Delocolization

Question 36

Delocalized electrons make metals good _____

Answer 36

conductors

Question 37

phase

Answer 37

a homogeneous part of a system that is separated from the rest of the system by a well defined boundary

Question 38

phase change

Answer 38

When a substance goes from one phase to another phase

Question 39

molar heat of vaporization (ΔHvap )

Answer 39

the amount of heat required to vaporize a mole of substance at its boiling point

Question 40

critical temperature

Answer 40

the temperature above which its gas cannot be liquified

Question 41

critical pressure

Answer 41

the minimum pressure that must be applied to liquefy a substance at its critical temperature

Question 42

fusion

Answer 42

melting

Question 43

melting point (freezing point) of a solid (or liquid)

Answer 43

the temperature at which the solid and liquid phases coexist in equilibrium.

Question 44

molar heat of fusion (ΔHfus )

Answer 44

the energy required to melt 1 mol of a solid.

Question 45

Sublimation

Answer 45

the process by which molecules go directly from the solid phase to the vapor phase.

Question 46

Deposition

Answer 46

the reverse process of sublimation

Question 47

molar enthalpy of sublimation (ΔHsub)

Answer 47

the energy required to sublime 1 mole of a solid.

Question 48

phase diagram

Answer 48

summarizes the conditions at which a substance exists as a solid, liquid, or gas

Question 49

triple point

Answer 49

the only combination of pressure and temperature where three phases of a substance exist in equilibrium.