Thermodynamics book review
19.39 which has higher entropy? d) CO21g2 or CO21s2.
CO2 gas
19.13: T or f: (d) An isothermal process is one in which the system loses no heat.
true
19.21 T of F: (a) ΔS is a state function.
true
19.45 In each of the following pairs, which compound would you expect to have the higher standard molar entropy: (a) C2H21g2 or C2H61g2 (b) CO21g2 or CO1g2?
(a) C2H61g2 (b) CO2(g)
19.13: T or f: (a) A reaction that is spontaneous in one direction will be nonspontaneous in the reverse direction under the same reaction conditions.
(a) True, assuming that the forward and reverse processes occur at the same conditions.
53 A. For a process that occurs at constant temperature, does the change in Gibbs free energy depend on changes in the enthalpy and entropy of the system?
(a) Yes. ΔG = ΔH - TΔS
53 c. (c) If ΔG for a process is large, is the rate at which it occurs fast?
(c) No. There is no relationship between ΔG and rate of reaction.
19.39 which has higher entropy? (c) 1 mol of Ne1g2 in 15.0 L or 1 mol of Ne1g2 in 1.50 L,
1 mol of Ne In 15 L
19.11 Which of the following processes are spontaneous and which are nonspontaneous: (a) the ripening of a banana, (b) dissolution of sugar in a cup of hot coffee, (c) the reaction of nitrogen atoms to form N2 molecules at 25 °C and 1 atm, (d) lightning, (e) formation of CH4 and O2 molecules from
All but e are spontaneous
19.39 For each of the following pairs, predict which substance has the higher entropy per mole at a given temperature: (a) Ar1l2 or Ar1g2, (
Argon gas
19.39 For each of the following pairs, predict which substance has the higher entropy per mole at a given temperature: b) He1g2 at 3 atm pressure or He1g2 at 1.5 atm pressure,
He gas at 1.5 atm
19.41: Predict the sign of entropy change of the system: (a) N21g2 + 3 H21g2¡2 NH31g2
S < 0
19.41: Predict the sign of entropy change of the system: (c) 3 C2H21g2¡C6H61g2
S < 0
19.41: Predict the sign of entropy change of the system: (d) Al2O31s2 + 3 H21g2¡2 Al1s2 + 3 H2O1g2
S = 0
19.41: Predict the sign of entropy change of the system: (b) CaCO31s2¡CaO1s2 + CO21g2
S > 0
19.35 Does the entropy of the system increase, decrease, or stay the same when (a) a solid melts, (b) a gas liquefies, (c) a solid sublimes?
S increases in (a) and (c); S decreases in
t or f:
The entropy of the universe increases for any spontaneous process.
what is the entropy of a pure, perfect crystalline substance at 0?
Zero
entropy
a measure of the tendency for energy to spread or disperse, thereby reducing its ability to accomplish work
53 b. For a certain process that occurs at constant T and P, the value of ΔG is positive. Is the process spontaneous?
b) No. If ΔG is positive, the process is nonspontaneous.
In any spontaneous process carried out at constant temperature and pressure, the free energy always what?
decreases
spontaneous processes that result in a decrease in the systems entropy are always what?
exothermic
19.13: T or f: (c) Most spontaneous processes are reversible.
false
19.13: T or f: b) All spontaneous processes are fast.
false
19.13: T or f:(e) The maximum amount of work can be accomplished by an irreversible process rather than a reversible one.
false
19.21 T of F:(b) If a system undergoes a reversible change, the entropy of the universe increases. (
false
19.21 T of F:(d) If a system undergoes a reversible process, the entropy change of the system must be zero.
false
19.25 T or F: The second law of thermodynamics says that entropy is conserved. (
false
19.25 T or F:(c) In a certain spontaneous process the system undergoes an entropy change of 4.2 J>K; therefore, the entropy change of the surroundings must be -4.2 J>K.
false
spontaneous process
is one that occurs on its own without any outside assistance.
common feature of spontaneous rxns
loss of potential energy
what type of rxns are MAJORITY of spontaneous
mostly exothermic
the reverse of a spontaneous rxn is always what?
non spontaneous
what does the change in entropy depend on
only on the initial and final states of the system and not on the path taken from one state to the other:
19.27 a. (a) What sign for ΔS do you expect when the volume of 0.200 mol of an ideal gas at 27 °C is increased isothermally from an initial volume of 10.0 L?
positive
what is S univ for a spontaneous rxn
positive (>0)
what must be not confuse spontaneity with?
speed, it doesn't mean that it occurs @ an observable rate
19.21 T of F:(c) If a system undergoes a reversible process, the change in entropy of the system is exactly matched by an equal and opposite change in the entropy of the surroundings.
true
19.25 T or F:(b) If the entropy of the system increases during a reversible process, the entropy change of the surroundings must decrease by the same amount.
true
t or f: Processes that are spontaneous in one direction are nonspontaneous in the opposite direction.
true
