Thermodynamics Flashcards
Reaction speed
How fast the reaction occurs
Spontaneous reaction
Reaction that occurs without outside intervention
No heating, no current, no catalyst
Entropy
A thermodynamic function that increases with the number of energetically equivalent ways to arrange the components of a system to achieve a particular state
S=k*ln(W)
The second law of thermodynamics
Given work in a closed system, the final state will always have less potential energy than the initial state
Everything tends to a point of lowest stored energy
Which means, for any spontaneous process, the entropy of the universe increases
Also that thermal energy cannot travel from a cold area to a warm area
And finally, in any closed system, the entropy of the system will either remain constant or increase, but never decreases
State function
The value depends on the state of the system
Entropy (S) by state
Gas> liquid> solid
Entropy of the universe
ΔHuniv=ΔHsys+ΔHsurr
Gibbs free energy
The amount of work that can be done from the available energy in a system
ΔG= ΔH -T(ΔS)
Zeroth law of thermodynamics
If two systems are each in thermal equilibrium with a third, they are also in thermal equilibrium with each other.
If A=B, and B=C, then A=C
First law of thermodynamics
The increase in internal energy of a closed system is equal to the difference of the heat supplied to the system and the work done by it: ΔU = Q - W
Which means that all energy is conserved, it cannot be created or destroyed, only transfered from one state to another
And by adding heat to the system, you either increase internal energy or you cause work to be done within the system
Gibbs free energy from equilibrium constant
ΔG=-RTln(K)
Gibbs free energy from standard cell potential
ΔG=-nFE.cell
Enthalpy
Sum of the internal energy to its pressure and volume
H=E+PV
Boltzman equation
S=k*ln(W)
Work from entropy
Ln(W)=S/k
Entropy of a gas
S=kh*P
Kh- henrys constant
Total Gibbs free energy in non-standard conditions
ΔG=ΔG°+RTln(Q)
Surroundings Entropy
ΔSsurr=-(ΔHsys)/T
Heat of reaction (ΔH)
ΔH=Σ(n)ΔHf{of products}-Σ(n)ΔHf{of reactants}
Otherwise
ΔH=ΔE-w
Or
ΔH=ΔG+T(ΔS)Observing a change in entropy (S)
See which state has a greater number of possible arrangements
Greater number of reactants/products or a decrease in temperature yields a greater entropy
ΔS of Surroundings
Because the reaction occured, the number of possible arrangements for molecules outside the given system changes
ΔSsurr=-ΔHsys/T
Relationships between ΔSsurr and ΔSsys
One is positive while the other is negative
Differ by the ΔG
ΔS of the universe
ΔSuni=ΔSsurr+ΔSsys
Thermodynamic properties of spontaneous reactions
Whenever ΔSuniv (so ΔSsys+ΔSsurr) is positive,
The reaction is spontaneous
Third law of thermo dynamics
As a system approaches absolute zero the entropy of the system approaches a minimum value and it is therefore impossible to reduce any system to absolute zero in a finite series of operations.
The entropy of a perfect crystal of an element in its most stable form tends to zero as the temperature approaches absolute zero.
Work
The use of energy to create a force
Given in NewtonMeters, the product of force and displacement or the integral of Force as a function of displacement when graphed against eachother
W=F*Δs=∫F(Δs)
