Reactivity 1.4 Flashcards
(15 cards)
What is entropy and its symbol?
S
a measure of distribution of energy in a system, disorder and randomness
How are particles in high entropy system?
particles spread out and move more
Why do systems tend to disorder?
more randomness as the energy is more dispersed
Entropy related to the 3 states of matter
least entropy: solid
mid: liquid
most entropy: gas
What happens to entropy during changes of state?
melting/vaporising: increase in ke, increases entropy
condensing/freezing: decreases ke, decreases entropy
Which changes of state cause an increase in entropy?
from solid to liquid to gas –> as gases have higher entropy
What effect does creating a solution have on entropy?
increases entropy
ions become dispersed between water molecules
In a chemical reaction, what do moles tell us about entropy?
increase in moles of gas -> increase in entropy and vice versa
What is the standard entropy of a substance?
entropy change from heating a substance from 0K to 298K
always positive, since at 0K entropy is 0
The more ways energy can be distributed…
The higher the entropy
The higher the entropy…
The more ways energy can be distributed
standard entropy change for a reaction =
standard entropy of the products - standard entropy of the reactants
What is a spontaneous reaction?
a reaction that occurs without the addition of energy other than the Ea
What is the 2nd law of thermodynamics? What does this imply?
the total entropy of the universe tends to increase
in a spontaneous process, energy goes from a concentrated form to a dispersed form
total entropy =
total entropy of system + total entropy of surroundings
