Spontaneous Change Chapter 10 Flashcards
Entropy (S)
measurement of randomness that occurs in particles
Change in S
Change in entropy between states
What does an increase in Entropy lead to ?
Spontaneous processes
Entropy Macroscopic Values
P, V, n, and T
3rd law of thermodynamics
S of a pure perfect crystal at 0k is 0
Equation of entropy
S= 0 when (Q/weird looking thing)= 1
Standard Molar Entropy Formula
Change in S = S prod - S reactants
It is equivalent to the change in enthalpy
2nd law of thermodynamics
Large molecules are assemebled from smaller ones and (Sf-Si univ) = (Sf-Si)sys + (Sf-Si)surr > 0
Change in Surr formula
dependent on change in enthalpy and change in temperature.
- Transferring energy to surroundings = lowest possible energy state for system.
- Energy transfer is maximized at lower temperature
(Sf-Si) = -(Hf-Hi)sys / T
What does it mean when change in Surr>0
It means reaction is irreversable because it will take on less entropy from surroundings.
Gibb-Helmholtz Equation
It’s a representation of a spontaneous and closed system.
(Gf-Gi) < 0
Formula (Gf-Gi) = (Hf-Hi) - T(Sf-Si)
3 possibilies in Gibb- Helmoholz equation
(Gf-Gi) < 0 ( Spontaneous) exergonic
(Gf-Gi ) > 0 (non spontaneous) endergonic
(Gf-Gi) = 0 Equilibrium
Entropy (S)
The measure of the number of microstates or unavailability to do work
Ex: Microstates: q/T
Gibbs Free energy
Maximum amount of work possible (available) in a closed, reversable system at constant T and P.
Ex: Enthalpy (H) Degrees of Freedom (S)
U-w-TS (leftover E)
Spontaneous processor
A process that is capable of proceeding in a given direction without outside intervention.
Examples: Combustion rxns. Once it starts it continues on its own
Or
Iron rust spontaneously in air.
Nonspontaneous Process
Will not occur without outside intervention.
Are Endothermic rxn be Spontaneous?
YES, Endothermic can be spontaneous and Exothermic rxns be non-spontaneous.
Example: The melting of ice is endothermic
or
The freezing of water is exothermic
Endothermic process formula
Examples (H2O) s –> (H2O) l
(Hf-Hi) fusion = 6.01 kJ/mol
Exothermic reactions
Example: (H2O) l —> (H2O) s
(Hf-Hi)fr = - (Hf-Hi)fus = -6.01 kj/mol
Table of Spontaneous rxns related to T>0
Melting Ice at 1 atm (Endothermic)
- T<0C: Nonspontaneous
- T = 0C: Reversable
- T > 0C: Spontaneous
Freezing water at 1 atm (Exothermic)
T<0 C: Spontaneous
T = 0C: Reversable
T> 0C: Nonspontaneous
Atoms, molecules, and ions tend to do what?
Spread themselves out
Homogenous gas mixtures are more likely to do compared to the state of two gases..
Be seperated
Entropy(S) change related to heat formula.
(Sf-Si) = qrev/ T
Process is reversable only if system is in equilibrium the entire process.
- Melting at melting point
- Vaporization at 1 atm at boiling point
(No temp change during process)
