what is entropy
a measure of the dispersal of energy in a system
the more disordered the particles the higher the entropy
between solids liquids and gases which has the highest entropy
gas then liquid then solid
as gases have the most random arrangement
how does the number of particles effect entropy
the more particles the more ways they and their energies can be arranged and therefore the higher the entropy
what causes the most amount of stability
higher entropy they are more energetically stable when there is more disorder
what does a positive entropy change of reaction mean
reaction is likely to be feasible
what is the equation for delta g
delta h - (T x delta s)
delta h = enthalpy change in jmol-1
t= temp in k
delta s= entropy change in kjmol-1
for a feasible reaction what must delta g be
negative
how can you predict a reaction is feasible
use the equation to see what values are positive and negative and what effect this has
what do you have to take into account when seeing if a reaction is feesible
the free energy says nothing about the rate if the activation energy is high then even if the reaction is feasible according to gibbs free energy it wont occur
how would you find delta h if not given it
q=m c delta t
delta h = q/n
as temp of a substance increases what does entropy do
increases
in a graph showing entropy on the y and temp on the x describe the line
vertical jump at 0 degrees c -melting point
bigger vertical jump at 100 degrees c -boiling point
what is important to remember
delta h and delta s NEED TO BE IN THE SAME UNITS
The exothermic reaction below occurs spontaneously at low temps but does not occur at very high temp
With increasing temp tdeltas is more negative
At high temp delta h - T delta s> 0
delta s
products-reactants
