Entropy and Enthalpy Flashcards
What is entropy?
amount of a disorder in a substance/ system
Measure of disorder
What impact does more disorder have on entropy?
higher
Which of solids, liquids and gases have the highest entropy?
gases > liquids > solids
How does entropy change with temperature?
entropy inc
Chaos / randomness inc
In the reaction
Li2CO3 (s) = Li2O (s) + CO2 (g)
Which is happening to the entropy?
Entropy is increasing
Positive change in entropy
Bc CO2 has a very high degree of disorder
In this reaction
SO2 (g) + 2H2S (g)
=
3S (s) + 2H2O (g)
Is the entropy inc or dec?
3 mol gas on LHS
2 mol gas RHS
More disorder on LHS
So entropy is dec so
Negative change in entropy
Units for entropy?
SJK-1MOL-1
What is the equation for calculating change in entropy?
Sum of products
Sum of reactants
SPAR
What type of entropy do solids have?
low entropy
What does a positive change in entropy indicate?
getting more disordered
What does a negative change of entropy indicate?
getting more ordered
What happens to entropy mean LHS is (s) and RHS is (aq)?
entropy inc
Enthalpy of entropy is positive
How do we know if a process is feasible at a given temperature?
Gibbs free energy is negative
What is the Gibbs free energy equation?
triangle G
= Enthalpy change
- T triangle S
How do you find the temp at which a reaction becomes feasible using Gibbs free energy?
set triangle G to 0
What reactions are always feasible?
exo
That get more disordered
Always feasible
Enthalpy change is negative
Enthalpy of entropy is positive
Gibbs free energy is always negative
What type of reactions are never feasible?
endo
Get less dissordered
