Entropy Theory Flashcards
Definition
A fundamental property of matter associated with disorder
“A measure of the disorder of a system/ space”
Unit for entropy
J K-1 Mol-1
What is the entropy of a perfect crystal at zero temperature
0 J K-1 mol-1
Put these in order from highest to lowest entropy:
Liquid, solid, gas
Gas, liquid, solid
Standard entropy values
298k at 25 degrees
Otherwise 273K
What causes increases and decreased in entropy
/\S+ or /\S-
Chemical changes
What shows within a reaction there will be a positive /\S value and what does this mean about the disorder
If there are more particles or gaseous atoms in the products there will be a +ve /\S
The disorder therefore increases
What is the thermodynamic law
And what does it state
The second law of thermodynamics
“All spontaneous processes increase the entropy of the universe until they reach equilibrium”
What is favoured in entropy
There is a net movement towards disordered arrangement
Any change increase the potential for disorder to be favoured
When are reactions more likely to be spontaneous
Why
Is this +ve or -ve entropy change
When the products have a greater entropy than the reactants.
As systems have tendency towards more disorder
These reactions have +ve /\S
What is required within /\Stotal to make a reaction spontaneous
For /\Stotal to be greater than 0 or positive
How does /\Ssurroundings change for exo and endo reactions
/\Ssurroundings increases with exothermic reactions as the temperature of surrounding particles increase.
Opposite for endothermic
Is /\Ssystem is negative what must be the case for a reaction to occur
/\Ssurroundings must be more positive
/\Stotal will be positive if..
Both /\ Ssurrounding and /\Ssystem are positive
Either /\Ssurrounding or /\Ssystem has a higher positive value than the other one which is negative
For a reaction to be spontaneous is /\G +ve or -ve
-ve
