8: Entropy and Gibbs Free Energy Flashcards
What is entropy?
A measure of how much disorder or chaos there is.
What does it mean if something is high in entropy?
There is more disorder.
Which state of a substance would have the most entropy?
Why?
Gases, they have the most energy and are free to quickly move around.
Generally, how is entropy as a whole changing in the universe?
Give an example using a glass.
Entropy is always increasing.
For example, glass could shatter, increasing its entropy, but could never fit itself back together.
Give the formula for calculating entropy change.
S = entropy of products - entropy of reactants
Give the units for entropy.
J K-1 mol-1
Give the units for enthalpy change.
Kj-1 mol-1
What minimum Gibbs free energy value is usually required for a reaction to be feasible?
It must be 0 or negative.
Give the equation used to calculate enthalpy change.
Enthalpy change = products - reactants
What is gibbs free energy used for?
It predicts whether a reaction is feasible or not.
What is a feasible reaction?
A reaction that continues fully to completion.
What 2 factors, aside from a negative Gibbs free energy value, can affect reaction feasibility?
High activation energy
Slow rate of reaction
Give the equation for Gibbs free energy.
DeltaG = Delta H - TdeltaS
Give the formula for finding the temperature a reaction becomes feasible at.
T = enthalpy change / entropy change
If a reaction is exothermic, will enthalpy change be positive or negative?
Negative enthalpy change