Unit 4: IMFs & Thermodynamics

Question 1

forces between particles (atoms, molecules, or ions) of a substance are called ________________

Answer 1

intermolecular forces

Question 2

bonds within molecules or formula units are called __________________

Answer 2

intramolecular forces

Question 3

the dominant forces between molecules are _____________

Answer 3

electrostatic

Question 4

dispersion forces are __________ and _____________ attractive forces between _____________ dipoles

Answer 4

very weak, very short range, temporary (induced)

Question 5

dispersion forces are the only forces between ___________ molecules

Answer 5

nonpolar

Question 6

dispersion forces are also called

Answer 6

London forces, van der Waals, or induced dipoles

Question 7

dispersion forces are __________ rather than ______________ dipole-dipole interactions

Answer 7

temporary; permanent

Question 8

polarizability ___________ with increasing numbers of electrons and, therefore, with increasing sizes of molecules

Answer 8

increases

Question 9

London forces are generally ____________ for molecules that are larger or have more electrons

Answer 9

stronger

Question 10

IMF result from attractive forces between regions of ____________ and ____________ charge density in neighboring molecules

Answer 10

positive, negative

Question 11

_________ interactions are so strong, they can even be considered intermolecular forces as well as intramolecular forces

Answer 11

ionic

Question 12

surface tension describes the inward forces that must be overcome in order to ________ the surface area of a liquid

Answer 12

expand

Question 13

viscosity increases as IMFs __________ in strength and as the temperature __________

Answer 13

increase; decreases

Question 14

the vapor pressure of all liquids ___________ with temperature

Answer 14

increases

Question 15

at room temperature, a liquid with ______ vapor pressure is called volatile

Answer 15

high

Question 16

diamond is a __________ crystal of carbon

Answer 16

covalent

Question 17

diamond and graphite are two _____________ forms of carbon

Answer 17

crystalline

Question 18

graphite forms __________ while diamond is ______________

Answer 18

flat sheets; tetrahedral

Question 19

the electrons in metallic solids are _____________

Answer 19

delocalized to form a “sea of electrons” that allow electricity (the movement of electrons) to flow freely

Question 20

First Law of Thermodynamics: During any physical or chemical change, the total amount of energy in the universe is __________

Answer 20

conserved (Law of Conservation of Energy)

Question 21

Total energy = __________ + ____________

Answer 21

kinetic energy, potential energy

Question 22

Total energy = __________ = ___________ + ___________

Answer 22

internal energy, heat energy, work energy

Question 23

State functions are a property of the system whose value depends ONLY on the __________ and ___________ states of system

Answer 23

initial, current
(symbols are capital letters)

Question 24

usually the reaction: the reactants and products

Answer 24

system

Question 25

the rest: the beaker, the air in the room, etc

Answer 25

surroundings

Question 26

system + surroundings

Answer 26

universe

Question 27

open system

Answer 27

exchange energy & matter

Question 28

closed system

Answer 28

exchange energy only

Question 29

isolated system

Answer 29

no exchange of energy or matter

Question 30

isothermal

Answer 30

constant temperature

Question 31

adiabatic

Answer 31

constant heat

Question 32

isobaric

Answer 32

constant pressure

Question 33

Internal energy is the sum of the _________ and ___________ energy of all _________ in the system

Answer 33

kinetic potential particles

Question 34

endothermic reaction: sign for q:

Answer 34

absorbing heat, q > 0

Question 35

exothermic reaction: sign for q:

Answer 35

gives off heat, q < 0

Question 36

positive work is work done __ system __ surroundings volume is __________

Answer 36

on, by, decreasing

Question 37

negative work is work done __ system __ surroundings volume is ___________

Answer 37

by, on, increasing

Question 38

specific heat is how much _________ is required to heat ____________ of a substance by one degree

Answer 38

heat, one gram

Question 39

heat of fusion is how much heat is required ________ __________ of a substance without changing the ___________

Answer 39

to melt one gram, temperature

Question 40

heat of vaporization is how much heat is required to __________ ________ of a substance without changing the ____________

Answer 40

vaporize one gram, temperature

Question 41

sublimation

Answer 41

solid to gas

Question 42

deposition

Answer 42

gas to solid

Question 43

unit for heat of vaporization

Answer 43

J/g

Question 44

___________ is heat at constant pressure

Answer 44

enthalpy change (∆H)

Question 45

heat of combustion is the _________ change for the combustion reaction in which _____ mole of the fuel is reacted

Answer 45

enthalpy, one

Question 46

calorimetry

Answer 46

an experimental technique to measure the energy change associated with a chemical or a physical process

Question 47

bomb calorimeter = constant ___________

Answer 47

volume

Question 48

coffee cup calorimeter = constant _____________

Answer 48

pressure

Question 49

standard ________ enthalpies of formation is enthalpy for reaction in which ____________ of a substance in a specified state is formed from its constituent elements in their ___________

Answer 49

molar, one mole, standard states

Question 50

larger atoms and molecules are more __________ than smaller atoms and molecules

Answer 50

polarizable

Question 51

__________ IMFs = most ideal gas

Answer 51

weaker

Question 52

the stronger the IMFs, the ________ the vapor pressure

Answer 52

weaker

Question 53

_________ IMFs = more viscosity

Answer 53

stronger

Question 54

nonmetals that melt below 500K are __________ solids

Answer 54

molecular

Question 55

nonmetals that melt above 500K are _________ solids

Answer 55

covalent

Question 56

breaking bonds ______ energy

Answer 56

absorbs

Question 57

forming bonds _______ energy

Answer 57

gives off

Question 58

ion-ion forces have a full and __________ charge

Answer 58

permanent

Question 59

hydrogen bonding has a partial and __________ charge

Answer 59

permanent

Question 60

third law of thermodynamics: the entropy of a ____________, _________________ substance at ____________ is zero

Answer 60

pure, perfect crystalline, absolute zero

Question 61

Gibbs Free Energy will always be ________ for spontaneous processes

Answer 61

negative

Question 62

when free energy is greater than zero, it is ______ stable

Answer 62

less

Question 63

when free energy is less than zero, it is _______ stable

Answer 63

more

Question 64

in a combustion reaction, heat is always ___________

Answer 64

released

Question 65

condensation

Answer 65

gas to liquid

Question 66

vaporization

Answer 66

liquid or solid to gas

Question 67

evaporation

Answer 67

liquid to gas

Question 68

for a given reaction, if ∆H (enthalpy change of the reaction) is _____________ and ∆S (entropy change) is ___________, then the value of ∆G (free energy) will ALWAYS BE NEGATIVE

Answer 68

negative, positive

Question 69

_________ law of thermodynamics: all _____________ changes are accompanied by an ___________ in universal entropy

Answer 69

second, spontaneous, increase

Question 70

reactions that occur spontaneously in one direction cannot occur spontaneously in the ___________ direction

Answer 70

reverse

Question 71

non-spontaneous means that entropy change is __________

Answer 71

negative

Question 72

entropy is a _____________ function that is a measure of the ____________ of energy

Answer 72

state, dispersal

Question 73

elements in their ____________ states will have change of free energy (∆G) equal to ___________

Answer 73

standard, zero

Question 74

third law of thermodynamics

Answer 74

the entropy of a pure, perfect crystalline substance at absolute zero is zero

Question 75

first law of thermodynamics (law of conservation of energy)

Answer 75

during any physical or chemical change, the total amount of energy in the universe is conserved

Question 76

standard states

Answer 76

how elements exist when they are at 1 atm pressure and 25 degrees Celsius

Question 77

molar heat of formation

Answer 77

the enthalpy change for the formation of one mole of product from its elements in their standard states

Question 78

the change in internal energy, ∆U, for a process is equal to the amount of heat __________ at constant ____________

Answer 78

absorbed, volume

Question 79

the change in enthalpy, ∆H, for a process is equal to the amount of heat ____________ or _____________ at constant __________

Answer 79

absorbed, released, pressure

Question 80

for a _____________ change, a positive change in entropy for the system is matched by a negative entropy change for the surroundings

Answer 80

physical