W7 Concept of thermodynamics Flashcards
w8 equilibrium
Zeroth Law of Thermodynamics
If two systems are in thermal equilibrium with a third system, the
two original systems are in thermal equilibrium with each other”
What is potential energy?
Any form of stored energy
What is kinetic energy?
Energy of moving objects
What is the First Law of Thermodynamics?
Energy cannot be created or destroyed, only transformed, from one form to another
Law of conservation of energy:
delta U = Q - W
where U= change in internal energy
Q- Heat added to system
W = Work done by the system
What is meant by Adiabatic?
No heat transfer
Internal energy changes only for work done or received by the system
What are the terms for constant volume and constant temperature?
Isovolumetric and isothermal
What is the Second Law of Thermodynamics?
“The Universe is always moving towards maximum disorder”
What is entropy (s) ?
A measure of disorder (dispersal in a system)
∆s = sf – si
If there is an increase in the number of microstates, then Wf > Wi and the entropy of the system increases ∆S > 0
If there is a decrease in the number of microstates, then Wf < Wi and the entropy of the system decreases ∆S < 0
Two Bulb Experiment:
Spontaneous process where gas expands to fill both bulbs equally, increasing entropy.
Is the energy higher for solids or liquids?
Liquids
(dispersal is higher as molecules are more separated)
Entropy: Solid < Liquid < Gas
Does increasing temperature affect entropy?
Yes- As temp inc, entropy inc as kinetic energy inc and therefore more dispersion
What increases entropy?
Inc temp
Changing state
Mixing of particle types
Why does entropy equal zero?
What temperature is absolute zero in ⁰C?
All vibrations and atomic movements
-273.15 ⁰C
What does Gibbs free energy predict?
∆G: Predicts if the reaction is spontaneous or not (at constant T and P)
When does a system come to equilibrium?
when it reaches its minimum Gibbs energy
What is Dynamic Equilibrium:
Reactions do not stop
when equilibrium is reached. The forward and backwards reactions continue to occur at the same rate. The overall proportion of R and P does not change.
What is the Equilibrium constant (K)
Describes the composition of a reaction
mixture when it comes to equilibrium
Reaction Quotient Q:
Measure of the composition of the reaction mixture as the reaction progresses – not at equilibrium
When is Q used?
When is K used?
Q= not at equilibrium
K= at equilibrium
For info:
If ∆Gr < 0, Q < K then the forward reaction proceed
If ∆Gr > 0, Q > K then the reverse reaction proceeds
If ∆Gr = 0, Q = K then the system is at equilibrium
