Reactions must obey the laws of thermodynamics: - My Class Sites

coralmonkeyMechanics

Oct 27, 2013 (3 years and 7 months ago)

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Reactions must obey the laws of thermodynamics:


The First Law of Thermodynamics



Energy cannot be created or destroyed, but it can transfer from
one object to another and it can be transformed from one form to
another (i.e. E
p

to E
k

), Thus, the total am
ount of energy in the
universe is constant.


The Second Law of Thermodynamics



The entropy of the universe must always increase. Reactions
must either directly or indirectly increase the entropy of the universe.



S
universe

=

S
sys

+

S
surr

, where

S
universe

> 0





-

students to class example, building macromolecules (gives off
energy which increase S
surroundings
.


The Third Law of Thermodynamics



The entropy of a perfectly ordered pure crystalline substanc
e is
zero at absolute zero.