gibbs free energy change (thermodynamics) Flashcards
what is entropy
the description of the number of ways atoms can share energy . If number of ways of arranging the energy is high then system is disorder and entropy is high
do solids liquids or gases have the highest entropy
gases because they are much more disordered
in general how will the entropy increase
- change of state from solid or liquid to gas
- significant increase in number of molecules between reactants and products
when do molecules have an entropy of 0
only perfect crystals at obsolete zero will have zero entropy
why is the entropy increased in exothermic reactions
The energy is given out into the surrounds
the number of ways of arranging the energy is therefore increased
how do you work out total entropy
S = Products - reactants
if the entropy is positive will the reaction be spontaneous
Yes
what’s the equation of gibbs’s free energy change
Delta G = Delta H - T x Delta S
for a spontaneous reaction what value does G need to be
A negative number
when is a reaction always feasible
a reaction that has positive entropy and is exothermic ( negative enthalpy )
Will increasing the temperature and entropy increase feasibility
If increase in entropy ( positive entropy)
Increase in temperature
G will be more negative
will the reaction be feasible if the temperature increases and entropy decreases
If entropy decreases then increasing temp will make it less likely that G is negative
will the reaction be feasible if entropy is close to zero and temperature increases
temperature does not have large effect as - TdeltaS will be snall
how can we use gibbs free energy equation in a graph
y=mx+c to the G=H-TxS
c = delta H
Gradient of the graph is equal to - delta S
what does the positive gradient mean on a graph for entropy
positive gradient means S is negative
