test 4

Question 1

true or false: not all chemical reactions involve energy changes

Answer 1

false

Question 2

area of chemistry dealing with applying thermodynamics principles to energy changes in chemical reactions

Answer 2

chemical thermodynamics

Question 3

ability to do work and change matter

Answer 3

energy

Question 4

law stating that energy can neither be created nor destroyed

Answer 4

law of conservation of energy

Question 5

energy of motion

Answer 5

kinetic energy

Question 6

energy associated with the position of an object and the forces acting upon it

Answer 6

potential energy

Question 7

the portion of the universe or the sample of matter being studied

Answer 7

system

Question 8

everything in the universe outside the system

Answer 8

surroundings

Question 9

sum of all the possible forms of energy of the ions, atoms, and molecules in a system

Answer 9

internal energy (E)

Question 10

thermodynamic property whose value is determined only by the state of the system

Answer 10

state function

Question 11

true or false: internal energy is independent of the path taken to reach a particular state and of the system’s history

Answer 11

true

Question 12

law stating that the energy gained (or lost) by a system equals the energy lost (or gained) by the surroundings

Answer 12

first law of thermodynamics

Question 13

transfer of energy as a result of a temperature difference

Answer 13

heat (Q)

Question 14

transfer of energy through a force applied across a distance

Answer 14

work (W)

Question 15

internal energy equation

Answer 15

ΔE = Q + W
(change in energy = heat + work)

Question 16

true or false: increases in internal energy mean ΔE is positive, and decreases in internal energy mean ΔE is negative

Answer 16

true

Question 17

SI unit of energy and energy transfer

Answer 17

Joule (J)

Question 18

internal energy plus the product of pressure and volume

Answer 18

enthalpy (H)

Question 19

enthalpy formula

Answer 19

H = E +PV
ΔH = ΔE + Δ(PV)
ΔH = ΔE + PΔV

Question 20

describes a process in which energy is absorbed and enthalpy increases

Answer 20

endothermic

Question 21

when heat is a reactant, the reaction is ________

Answer 21

endothermic

Question 22

if ΔH is positive, the reaction is ________

Answer 22

endothermic

Question 23

describes a process in which energy is released and enthalpy decreases

Answer 23

exothermic

Question 24

if heat is a product, the reaction is _______

Answer 24

exothermic

Question 25

if ΔH is negative, the reaction is ________

Answer 25

exothermic

Question 26

total energy released or absorbed between the start of a reaction and its end

Answer 26

enthalpy of reaction (ΔH)

Question 27

chemical equation written to show the change in enthalpy

Answer 27

thermochemical equation

Question 28

normal physical state of an element at 100 kPa and a specified temperature

Answer 28

standard state

Question 29

any element in its standard state at the specified temperature has an assigned enthalpy of _______

Answer 29

zero

Question 30

enthalpy change for a reaction in which 1 mol of a compound is formed from its elements in their standard states

Answer 30

standard enthalpy of formation (ΔfH°)

Question 31

law stating that when a series of reactions occurs, the enthalpy of the net (overall) reaction is the sum of the individual reactions’ enthalpies

Answer 31

Hess's law

Question 32

Hess's law formula

Answer 32

ΔH° = ΔfH° (products) - ΔfH° (reactants)

Question 33

heat required to cause a unit rise in the temperature of a unit mass of a substance

Answer 33

specific heat (c)

Question 34

specific heat formula

Answer 34

c = Q / mΔT

Question 35

formula to solve for heat

Answer 35

Q = mcΔT

Question 36

specific heat of water

Answer 36

4.18 J / grams degrees Celsius

Question 37

graph that shows temperature as a function of energy added as heat

Answer 37

heating-curve graph

Question 38

energy per unit mass required to melt a substance at its melting point

Answer 38

enthalpy of fusion (ΔfusH)

Question 39

energy per unit mass required to vaporize a substance at its normal boiling point

Answer 39

enthalpy of vaporization (ΔvapH)

Question 40

negative heat of fusion

Answer 40

enthalpy of crystallization

Question 41

negative heat of vaporization

Answer 41

enthalpy of condensation

Question 42

formula to find heat of vaporization

Answer 42

Qvap = mΔvapH

Question 43

formula to find heat of fusion

Answer 43

Qfus = mΔfusH

Question 44

two rates that offset each other; looks like nothing is occurring, but it is

Answer 44

dynamic equilibrium

Question 45

pressure exerted by a vapor when it is in equilibrium with a liquid phase of the same substance

Answer 45

vapor pressure

Question 46

true or false: increased temperature increases the vapor pressure

Answer 46

true

Question 47

temperature at which a liquid’s vapor pressure equals the total pressure of all gases present

Answer 47

boiling point

Question 48

certain combination of pressure and temperature above which the distinction between liquid and gas disappears

Answer 48

critical point

Question 49

combination of temperature and pressure at which all three phases of a substance are in equilibrium

Answer 49

triple point

Question 50

formed when a substance is at the point the distinction between liquid and gas is gone

Answer 50

supercritical fluid

Question 51

true or false: systems tend to increase their stability by going to LOWER potential energy states

Answer 51

true

Question 52

able to occur without continuing outside help

Answer 52

spontaneous

Question 53

measure of the disorder or randomness of a system's atoms and molecules

Answer 53

entropy (S)

Question 54

law stating that the entropy of the universe is always increasing

Answer 54

second law of thermodynamics

Question 55

true or false: processes for which the change in entropy (ΔS) is negative tend to be spontaneous

Answer 55

false; if the change is positive it will be spontaneous

Question 56

describes objects in thermal equilibrium

Answer 56

zeroth law of thermodynamics

Question 57

a state in which no heat flows between the object the objects because they are at equal temperature

Answer 57

thermal equilibrium

Question 58

law that states it is absolutely, not just practically, impossible to cool a system to absolute zero in finite time

Answer 58

third law of thermodynamics

Question 59

out of enthalpy and entropy: __1__ tends to decrease, and __2__ tends to increase

Answer 59

1. enthalpy 2. entropy

Question 60

1. If enthalpy is negative and entropy is positive, it will be _______ 2. If enthalpy is positive and entropy is negative, it will be ________

Answer 60

1. spontaneous 2. nonspontaneous

Question 61

formula for Gibbs free energy (G)

Answer 61

ΔG = ΔH - TΔS

Question 62

A process at constant temperature and pressure is spontaneous as written if and only if ΔG is _______

Answer 62

negative

Question 63

At low temperatures, __1__ is the more important term, whereas at higher temperature, __2__ becomes more important

Answer 63

1. enthalpy 2. entropy

Question 64

state such that ΔG has a value of zero

Answer 64

equilibrium

Question 65

both the forward and reverse processes occur, but because they occur at equal rates, there is no net change in the system

Answer 65

dynamic equilibrium