A2.5 Enthalpy And Entropy Flashcards
1
Q
Entropy
A
A measure of the dispersal of energy in a system which is greater the more disordered a system
S
Every substance has positive entropy value
2
Q
Sign of entropy changes depends on
A
How states change
Gas > liquid > solid
How moles change
More moles of gas = positive change
3
Q
Calculating entropy change
A
^S = products - reactants
Consider moles
4
Q
Feasibility of a reaction
A
Once started, it will carry on to completion without any energy being supplied to it
5
Q
Feasibility depends on……
A
Temperature
Entropy
Enthalpy
6
Q
A reaction is feasible when…..
A
Free energy change has a value of <= 0
7
Q
^G
A
Free energy
^H - T^S
8
Q
Calculate temperature at which feasibility changes
A
T = ^H / ^S
9
Q
Feasibility straight line
A
Y = mx + c
^G = -^S T + ^H
