Chapter 16 Thermodynamics Textbook Flashcards
A spontaneous process
one that occurs naturally under certain conditions
A nonspontaneous process will not take place unless
will not take place unless it is “driven” by the continual input of energy from an external source
A process that is spontaneous in one direction under a particular set of conditions is —- in the reverse direction
nonspontaneous
The spontaneity of a process is not correlated to the —-
speed of the process.
A spontaneous change may be so rapid that it is essentially instantaneous or so slow that it cannot be observed over any practical period of time.
kinetically stable+ex
If the activation energy is high, the reaction is kinetically stable.
If it is not able to change forms in a short time (Ex: Dimonds to graphite takes long time so its kinectically stable.
thermodynamically unstable
There exists a state where the system will have lower energy than it currently has. (spontaneous)
When two objects at different temperatures come in contact, heat spontaneously flows from
the hotter to the colder object.
graphitization
The conversion of carbon from the diamond allotrope to the graphite allotrope
The phase diagram indicates that
graphite is the stable form of this element under ambient atmospheric pressure, while diamond is the stable allotrope at very high pressures, such as those present during its geologic formation.
Diamonds are said to be
diamonds are said to be thermodynamically unstable but kinetically stable under ambient conditions.
Two flask connected by a closed valve, tell me about the work, heat, internal energy, and what is sponetatey not a consequence of? (4)
- The work is 0 because pressure in a vaccum is zero.
- The heat is 0 since the system is isolated
- The first law of thermodynamics confirms that there has been no change in the system’s internal energy as a result of this process.
- The spontaneity of this process is therefore not a consequence of any change in energy that accompanies the process.
What is the driving force of the spontaneity of the 2 valve process? (2)
Initially…..
- greater, more uniform dispersal of matter that results when the gas is allowed to expand
- Initially, the system was comprised of one flask containing matter and another flask containing nothing. After the spontaneous expansion took place, the matter was distributed both more widely (occupying twice its original volume) and more uniformly (present in equal amounts in each flask).
an important factor in determining the spontaneity of a process is—— for example——
- the extent to which it changes the dispersal or distribution of matter and/or energy
- a spontaneous process took place resulted in a more uniform distribution of matter or energy.
reversible process
one that takes place at such a slow rate that it is always at equilibrium and its direction can be changed (it can be “reversed”) by an infinitesimally small change in some condition.
entropy (S)+formula with heat+what it is (3)
-State function
-Engery. unable to do work
*heat divided by temperature
Low entropy
energy is concentrated
High entropy
Energy is spread out
microstate (2)
a specific configuration of all the locations and energies of the atoms or molecules that make up a system
The arrangement of each molecule in the system at a single instant.
The relation between a system’s entropy and the number of possible microstates is
where k is the Boltzmann constant, 1.38 10^−23 J/K.
The most probable distribution is the one with
*Not entropy
the most mircostates
CHANGE in entropy formula
When entropy increases what happens to final/initial/microstates/ΔS ?
For processes involving an increase in the number of microstates, Wf > Wi, the entropy of the system increases and ΔS > 0.
Conversely, processes that reduce the number of microstates, Wf < Wi, yield a
decrease in system entropy, ΔS < 0
Processes that reduce the number of microstates Wf < Wi, yield a
yield a decrease in system entropy, ΔS < 0