free energy, spontaneity, and entropy Flashcards
entropy is a measure of _____ or _____
randomness or disorder
The driving force for a spontaneous process is an
_______ of the universe
increase in the entropy
a thermodynamic function describing the
number of arrangements that are available to a system
Entropy
The first law of thermodynamics
Law of Conservation of Energy
Energy can be neither created nor destroyed. In other words, the energy of the universe is constant.
Energy in Chemical reactions
A + B → C + D + Energy
A + B → C + D + Energy
The potential energy is the chemical bonds of C and D is ____
lower
The excess has been given off (energy) as thermal energy, or heat, which is kinetic energy transferred to the surroundings
- Processes that occur without outside intervention
- may be fast or slow
Spontaneity / Spontaneous Processes
*Many forms of combustion are ___
*Conversion of graphite to diamond is ____
fast; slow
Kinetics is concerned with _____,
thermodynamics with the _____
speed; initial and final state
Second Law of Thermodynamics
▪ “In any spontaneous process there is always an increase in the entropy of the universe”
▪ “The entropy of the universe is
increasing”
For a given change to be spontaneous, ΔS universe must be _____
positive
ΔS universe = ΔS system + ΔS surroundings
The probability of occurrence of a particular state depends on the number of ways (microstates) in which that arrangement can be
achieved
Positional Entropy
S solid < S liquid «_space;S gas
Entropy changes in the surrounding are primarily determined by _____
heat flow (temperature)
temperature affects entropy indirect relationship
in exothermic process, if ΔS surroundings is ______
positive; more disorder in surroundings
The lower the temperature, the _____ the impact to the surroundings of the transfer of energy
higher
mas malamig, mas mataas impact sa transfer of energy
in endothermic process, if ΔS surroundings is ______
negative; less disorder in surroundings
Typically defined as the energy available to perform work
free energy
when ΔG is negative, the process is
spontaneous
Free energy takes into account ____, ____, and ____
enthalpy, entropy, and temperature
name of Gibbs
Josiah Gibbs
The products have a lower free energy (G) than the reactants
spontaneous
The reactants have a higher free energy than the products (ΔG)
nonspontaneous
ΔG = 0
The reaction mixture is at equilibrium.
-It’s not moving forward or reverse overall
– multiple processes, same speed
Spontaneity can change when the temperature changes but
Temperature and spontaneity are not necessarily correlated.
Free energy (G) values tell us if reactions will occur and not
how fast reactions will occur
During a reaction
– Reactant particles must
physically collide with enough energy to break the bonds in the reactant
more moles of gas
more entropy
Third Law of Thermodynamics
*“The entropy of a perfect crystal at 0 K is zero” (NO disorder, since everything is in perfect position)
no movement = 0 K = no entropy
standard state conditions
Pure solids/liquids/gases at 1 atm pressure
Solutes at 1 M concentration
Typically @ 25 °C (298 K)
Designated by ° sign (similar to degree sign)
Entropy is a/n ______ property
extensive
the more complex the molecule
the higher the standard entropy value
the lowest possible free energy position for a reaction
equilibrium
ΔGf of an element in its standard state
zero
entropy vs enthalpy
entropy is pressure (volume) dependent
Volume ↑ Pressure↓ Entropy ↑
Henry’s Bent’s First Two Laws of Thermodynamics
- 1st Law: You can’t win, you can only break even
- 2nd Law: You can’t break even
