3.1.8.2 - gibbs free - energy change, 🔼G and entropy change Flashcards
what is a feasible reaction
A reaction that can occur at a particular temp. + once started will carry
on to completion w/out any energy being supplied to it is called a
define entropy
a measure of disorder w/in a system.
units of entropy
J K-1 mol-1
3 factors affecting entropy
physical state
dissolution
number of particles
describe how physical state affects entropy
gases are more disordered than liquids and solutions.
Liquids and solutions are more disordered than solids. So, with that,
physical state affects entropy
describe how dissolution affects entropy
dissolving a solid increases its entropy as dissolved
particles can move freely because they are no longer held in fixed
positions.
describe how number of particles affects
more moles of particles increased entropy. The
more particles there are, the more ways they, and their energy can be
arranged.
the higher the absolute entropy value the …
the higher the degree of disorder
of a substance. Therefore gases have the highest absolute entropy value.
equation for entropy change
∆S = [sum of ∆SƟ products] - [sum of ∆SƟ reactants]
equation for gibbs free energy change
∆G = ∆H – T∆S
Gibbs free-energy change, ∆G, is a measure…..
used to predict whether a
reaction is feasible.
For a reaction to be feasible, the value of ∆G….
must be equal to or less
than zero (i.e. 0 or -ve)
change in g =
changeH - TchangeS
unit conversions for change S
divide by 1000 to get kj
temp=
change in HS
