Entropy Flashcards
What is entropy?
A measure of disorder within a system
As we move from solid to liquid to gas what happens to entropy?
Entropy is increasing as particles have more freedom of movement and more disorder
What happens to entropy when we heat a sample up?
Entropy increases, as the particles have more kinetic energy and hence more disorder
What happens to entropy if I increase the concentration of a gas or liquid?
Entropy increases due to greater number of arrangements of molecules
What is the equation for entropy change in a system?
Sum of entropy of products, take away sum of entropy of reactants
What units is entropy measured in?
Joules per Kelvin per mol
If a system loses energy by increasing the entropy then the sign for entropy change will be?
Positive +ΔS
How do we calculate the total entropy change of a reaction?
ΔStotal = ΔSsys + ΔSsurr
If ΔSTotal is positive the reaction is…
spontaneous or feasible.
If ΔStotal = 0 then the reaction is at …
equilibrium, this is the value we use to find the minimum temperature when the reaction can occur
Do we always need to give a + or - sign in an answer?
Yes! always
How do we calculate the entropy change of the surroundings?
ΔSsurr = -ΔHr / T
T is always measured in
Kelvin 273 K = 0oC
Enthalpy change is always given in …
kJ per mol
Entropy questions can catch students out with units by ….
Using Joules for entropy and kilojoules for enthalpy, convert!
