thermochem2

Question 1

proceeds without any outside assistance
processes that are spontaneous in one
direction are * in the
reverse direction

Answer 1

spontaneous process

nonspontaneous

Question 2

entropy
measure of the * in a system
energy and matter tend to become more *
* function

Answer 2

randomness
disordered
state function

Question 3

ΔS = Sfinal - Sinitial

If the change from initial to final results to an increase
in randomness:

If the change from initial to final results to a decrease
in randomness:

Answer 3

Sf > Si ΔS > 0 (positive)

Sf < Si ΔS < 0 (negative)

Question 4

§ measures disorder

S (s) < S (l) &laquo_space;S (g)
S (aq) usually between liq and gas

§ increases with * temperature

Answer 4

increasing

Question 5

second law of thermodynamics:
the entropy of the universe *
in any * processes such that

Answer 5

increases, spontaneous

ΔSuniv > 0

Question 6

a single possible arrangement of position

and kinetic energy of molecules

Answer 6

microstate

Question 7

RELATIONSHIP BETWEEN ENTROPY AND MICROSTATES

*

Answer 7

S = k ln W

Question 8

use statistical thermodynamics to relate bulk
properties to events on the molecular scale
à involves probabilities
à entropy increases with the number
of microstates of the system

Answer 8

ENTROPY ON THE MOLECULAR SCALE

Question 9

* in ENTROPY
• Phase change from solid to
liquid.
• Phase change from liquid to gas.
• Phase change from solid to gas.
• Solute dissolving in a solvent.
• Diffusion of gases.
• Increase in temperature of
system.

Answer 9

INCREASE

Question 10

When gases are involved…

Ø If a reaction produces more gas molecules than it
consumes, *

Ø If the total number of gas molecules diminishes,
*

Ø If there is no net change in the total number of
gas molecules, then ΔS0 may be positive or
negative BUT ΔS0 will be a small number.

Answer 10

ΔS0 > 0.

ΔS0 < 0.

Question 11

the entropy of a * at absolute zero is 0

Answer 11

third law of thermodynamics
pure crystalline
substance

Question 12

STANDARD MOLAR ENTROPY

§ reference temperature for entropy is 0 K,
so values for elements are not 0 J/mol K at 298 K

§ generally greater for * than liquids and solids

§ increases with *

§ increases with number of * in a formula

Answer 12

gases
molar mass
atoms

Question 13

entropy changes for a reaction can be calculated in a
manner analogous to that by which DH is calculated:

where n and m are the coefficients
in the balanced chemical equation

Answer 13

delta S = summation (s products) - summation (s reactants)

Question 14

heat that flows into or out of the system
changes the entropy of the surroundings

for an isothermal process:

Answer 14

delta s = q(sur)/T = -q(sys)/T

Question 15

at constant pressure,

qsys is simply deltaH° for the system:

Answer 15

delta s = -deltaH(sys)/T

Question 16

“The entropy of the universe increases in a
spontaneous process and remains unchanged in an
equilibrium process.”
Spontaneous Process: ΔSuniv =
Equilibrium Process: ΔSuniv =

Answer 16

Spontaneous Process: ΔSuniv = ΔSsys + ΔSsurr > 0

Equilibrium Process: ΔSuniv = ΔSsys + ΔSsurr = 0

Question 17

the maximum amount of useful work which
can be extracted from a closed system
formula

Answer 17

gibbs free energy

G = H – TS

Question 18

ΔGº = ΔHº - TΔSº

Answer 18

mem

Question 19

is the process spontaneous?
ΔGº 
forward reaction is spontaneous
ΔGº
the system is at equilibrium
ΔGº 
forward reaction is nonspontaneous
(but spontaneous in the reverse direction)

Answer 19

is the process spontaneous?
ΔGº < 0
forward reaction is spontaneous
ΔGº = 0
the system is at equilibrium
ΔGº > 0
forward reaction is nonspontaneous
(but spontaneous in the reverse direction)

Question 20

analogous to standard enthalpies of formation
are standard free energies of formation, ΔGºf:
formula

Answer 20

copy

Question 21

ΔfGº for an element is *!

Answer 21

zero

Question 22

free energy function is also dependent on *
in certain instances, reactions can be
product−favored at equilibrium at one temperature
and reactant−favored at another

Answer 22

temperature

Question 23

spontaneity of a process can be predicted

from the signs of DH and DS

Answer 23

table