Entropy Flashcards
What is entropy?
A measure of disorder in a system
A measure of the number of ways energy can be shared out between particles
Symbol of entropy
S
Increase in entropy will mean…
An increase in entropy
What affects the entropy of a system?
The state it’s in
Number of particles (moles)
How does the states effect entropy?
Enthalpy will decrease from: gases>liquid>solids as the particles are more disordered, larger distance between molecules
So if in a reaction we go from solid——> gas entropy will increase
How does number of particles affect entropy?
Entropy increases as there are more ways energy can be distributed if the no. Of moles increases
Even if the states stay the same
What does it mean for a reaction to be feasible?
Can happen spontaneously in spite of unfavourable enthalpy conditions such as low temperature
What will reactions always tend to lean towards?
More disorder thus an INCREASE in entropy
Requires less energy
Can endothermic reactions that are less enthalpically favourable still be feasible?
Yes if changes in entropy will overcome changes in enthalpy
Symbol for entropy change
🔺S
Entropy change of system symbol
🔺Sₛᵧₛₜₑₘ
How to calculate entropy change of a system of a reaction?
=total entropy of products - total entropy of reactants
By adding standard entropy values together
What are standard entropy values?
A measure of the change in entropy from natural way of order: increasing entropy (randomness)
So will always be a positive value
Units for change in entropy system
J K-1 mol-1
What do we remember when calculating the entropy change of a system?
The positive or negative sign:
Increase in entropy (positive)
Or decrease in entropy (negative)
Multiply based on molar ratio
