L3-L5 Flashcards
Natural changes occur in only one ____. All spontaneous processes are ____ and result in a ___ of usable work. However, a spontaneous process does not need to be ____.
direction, irreversible, loss, fast
Nonspontaneous changes can be made to happen in the ____ direction. A spontaneous change can be reversed only by doing ____
unnatural, work
For a reversible process, the entropy of universe is equal to _____. For a spontaneous process, the entropy of the universe is ___ than 0.
0, greater
a measure of disorder (numbers of microscopic ways to realize a macroscopic state).
entropy
A change in entropy can be calculated by the energy transferred as ___ in a ____ process divided by the ___ at which the process occurred. If the process is ____, we must devise a ____ reversible path (potentially including many steps) between the same initial and final states to calculate entropy for the process.
heat, reversible, temperature, irreversible, hypothetical
The surroundings act as a perfect ___ __ with ___ heat capacity. Thus, the irreversible heat balance of the system always corresponds to a _____ heat balance of the surroundings
heat sink, infinite, reversible
The entropy of an ____ ___ increases in the course of any ____ process
isolated system, spontaneous
For isochoric or ____ reversible processes, an increase in ____ corresponds to an increase in the ___ __ of molecules (entropy)
isobaric, temperature, thermal motion
For an isothermal reversible process, an increase in _____ or ____ with other substances results in an increase in entropy
volume, mixing
For an ____ reversible process, the q = ___ and thus both the system and surroundings entropy is ___
adiabatic, 0, 0
An adiabatic process that is ___ and ____ will ___ in entropy
isolated, irreversible, increase
Trouton’s rule for liquids
Svap = 85 J/K mol
The third law of thermodynamics shows that at ____ K, all perfect crystals in equilibrium have the same ____. It is defined as ___. At temperatures higher than zero, more different ___ ___ become available to the molecules for the same ____ state, thus the entropy will be _____ than zero.
0, entropy, 0, microscopic arrangements, macroscopic, greater
Statistical thermodynamics, or ______ was proposed by Austrian Physicist Ludwig Boltzman in 1877. ____ is the number of ___ ____ available to the system for a macroscopic state of given internal energy. For a perfect crystal at 0K, there is only ___ way of arranging the molecules. The boltzman constant is related to the gas constant by _____.
S = kb ln (ohm), ohm, microscopic states, one, R = kNa
Gibbs free energy can allow us to assess whether a process is ___ or not, only from properties of the ___ alone. This is under the condition that ___ and ___ are both constants during the entire process
spontaneous, system, pressure, temperature
Gibbs free energy is a ___ function.
state
It constant pressure and temperature, spontaneous processes are accompanied by a ___ in gibbs energy of the system. Equilibrium conditions (conditions for ____) are reached when Gibbs free energy is equal to ____
decrease, reversibility, 0
the standard molar gibbs energy of formation can be calculated from its formation from its _____ in their __ __ at a given temperature and pressure. The standard molar gibbs energy of formation of an element in its most stable ___ form at 1 bar and ____ K is ____
elements, standard states, allotropic, 298, 0
The temperature dependence of the gibbs energy can be calculated from the temperature dependence of the __ and ____. Very often, we assume these are ___ of the temperature
enthalpy, entropy, independent
G allows us to determine the amount of ___ that can be done in a given process, as it is equal to the ___ ___ ____ the system can do during a process at constant pressure and temperature
work, maximum non-expansion work
mu is the ___ __ of a substance i. It is the partial ___ ___ __ of this substance. (the molar contribution of substance i to the ____ gibbs energy of a mixture). This is a measure of the ability of substance i to bring about __ ___. A high chemical potential of a substance is an indication that this substance is __ ___
chemical potentially, molar gibbs energy, total, chemical change, chemical active
A P,T-diagram shows the regions in which each phase is the most _____. At the phase boundaries, the two phases separated by the border line are in _____
stable, equilibrium
where solid and liquid are in equlibrium
fusion curve
where solid and gas are in equilibrium; the sublimation vapor pressure of a solid is the pressure of the vapor in equilibrium with the solid at a particular temperature
sublimation curve
equilibrium between liquid and gas; the vapor pressure of a liquid is the pressure of the vapor in equilibrium with the liquid at a particular temperature.
vaporization curve
The vapor pressure is function of ___ only
temperature
temperature at which the liquid and solid phase coexist in equilibrium at a specified pressure.
melting / freezing point
When Pex on the sample is 1 atm, the melting / freezing temperature is called the ____ melting / freezing point
normal
temperature at which the vapor and liquid phase coexist in equilibrium at a specified pressured
boiling / condensation point
Every point on the fusion curve indicates a ___ ___ for a different ____. Every point on the vaporization curve indicates a __ ___ for different pressures
melting point, pressures, condensation/boiling point
the degrees of freedom available to a system; the numbers of independent state functions to define the system
F
number of chemical components in the system
c
the number of phases present in equilibrium of the system
P
In one component phase-diagrams, if only a single phase is present, P = ____, then F = ___. Thus, both __ and ___ can be varied independently.
1, 2, temperature, pressure
In one component phase-diagrams, if 2 phases are present simultaneously, then F = ___, so that along any phase boundary line, there is only ___ degree of freedom. If we specify that 2 phases are in equilibrium at some value of _____, P is absolutely ___ and no longer an independent or free variable of the system
1, 1, temperature, fixed
the point where 3 phases are in equilibrium simultaneously
triple point
the point where above a certain temperature, no matter how high the pressure is, the substance can no longer be a liquid.
critical point
A substance present in the critical point is called a _______ ___. It is neither a ___ or ___, but with a density like that of a ____
supercritical fluid, gas, liquid, liquid
At the critical point, the supercritical fluid exists, with the density of the liquid = to the density of the ____. The ___ between liquid and gas disappears completely, and the states become ___ and ____. The critical point signals the highest ____ are which liquid can exist.
gas, interface, identical indistinguishable, temperature
Matter in the SCF condition show very different physical properties from the ___ state. SCF ____ has been used to produce decaffeinated ___< replacing the traditional hazardous ____ solvent
gaseous, CO2, coffee, CH2Cl2
the clausius calpeyron equation gives a expression for ___ as a function of ___ when two phases A and B are in ____ (phase boundaries)
pressure, temperature, equilibrium
If the vaporization ____ is considered to be ___ of t and p, the volume of the ___ is treated to be much more than the liquid, and the vapor is treated as an __ ___, the C-C equation is reduced to _____
enthalpy, independent, gas, ideal gas, V = RT/p
Non ideal behaviour is described by replacing the concentration with the _____ _____. It depends on ___, ____, all the concentrations, and on the choice of the __ ____. In standard state, the activity coefficient equals to ___ by definition. Activity has no ___
activity coefficient, pressure, temperature, standard state, 1, unit
mole fraction
n/total number of moles of all particles in the system
For Q, use the actual activities during the ___ reaction process. For K, use the activities only when the reaction is in ____
entire, equilibrium
For solids and liquids, activity equals ____
1
if the change in gibbs free energy of the reaction is greater than 0, the ____ reaction is spontaneous, while if it is lower than 0, the _____ reaction is spontaneous
reverse, forward
K can only be calculated from the ____ ___ ____ energy, which in turn can be calculated from tabulated values. K is a function of ___ only.
standard gibbs reaction, temperature
The second law of thermodynamics says that in any possible process, the total entropy change of the universe can never be ____.
negative
It is _____ to convert heat completely to work, because work is a process to move ___ ____ into more ordered ones.
impossible, random motions
It is often extremely difficulty to apply the second law in reality,
because you have to know the entire _____ before you can decide whether a “proposed” process is ______
universe, spontaneous
The second law also infers that the system receives the ____ amount of heat, and does the ____ amount of work (to the surroundings) under _____ conditions
maximal, maximal, reversible
In an enthalpy driven reaction, both enthalpy and entropy are ____, and the reaction is only spontaneous at ___ temperatures.
negative, low
in an entropy driven reaction, both enthalpy and entropy are ___, and the reaction is spontaneous only at ___ temperatures
positive, high
Maximum work can only be realized if the process is carried out along a
_____ (infinitely ____) path. Along a reversible path, the system is near equilibrium and a small incremental change in a variable will bring the system back to its _____ state. Any real process is irreversible, thus cannot yield ______ work. In
reality, the amount of work available is always ____ than maximum for any real (irreversible) change.
Therefore, change in G reveals how much maximum energy is ____ ____ to do something humans want to perform in an ____ (useful) way, for example, through electrical work.
reversibly, slow, initial, maximum, less, freely available, ordered
the ___ value of G for ___ ___ indicates that this process is ______ at standard state. However, if temperature is greater than ____ K, the polymer will automatically ___ back to monomers. Thus, it take considerable amount of energy to heat up ____ ___ to reuse the resulting monomers afterward
negative, polymer formation, spontaneous, 479K, recycled polymers
If the reaction is enthalpy driven, the reaction is only spontaneous at T ___ enthalpy/entropy, while if the reaction is entropy driven, the reaction is only spontaneous at T ___ enthalpy / entropy
<, >
The Vant hoff equation applies to any ___ process. The CC equation applies only to ___ and ___ processes during which ____, because the activities of solids and liquids = ____
general, vaporization, sublimation, K=P, 1
Even if the change in standard gibbs free energy is greater than ____, some forward reaction must occur such as ______.
0, K > 0
change in standard gibbs free energy does not dictate the ___ of a process in general, it only determines the value of ___. Only when _______, or all things are in their standard states, does this determine the spontaneity
spontaneity, K, Q=1
Reaction will always occur regardless of the ____ of change in standard gibbs free energy, but the extent of the reaction, ___, is governed by change in standard gibbs free energy, and the reaction will reach equilibrium when _____
sign, K, K=Q
