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G12 Entropy

This document discusses spontaneous and nonspontaneous reactions and processes. It defines a spontaneous reaction as one that occurs under specified conditions, while a nonspontaneous reaction does not occur under the same conditions. Several examples are given of processes classified as spontaneous or nonspontaneous, including a waterfall, ice melting, and heat transfer. The document then introduces entropy as a measure of disorder or randomness in a system. Processes that increase entropy, like melting, vaporization, dissolving, and heating, are classified as spontaneous. Gibbs free energy is also introduced as another thermodynamic property used to predict spontaneity based on calculated values.

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166 views42 pages

G12 Entropy

This document discusses spontaneous and nonspontaneous reactions and processes. It defines a spontaneous reaction as one that occurs under specified conditions, while a nonspontaneous reaction does not occur under the same conditions. Several examples are given of processes classified as spontaneous or nonspontaneous, including a waterfall, ice melting, and heat transfer. The document then introduces entropy as a measure of disorder or randomness in a system. Processes that increase entropy, like melting, vaporization, dissolving, and heating, are classified as spontaneous. Gibbs free energy is also introduced as another thermodynamic property used to predict spontaneity based on calculated values.

Uploaded by

Kara Barbosa
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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GEN.

CHEMISTRY 2
A reaction that
does occur under
WHAT IS
SPONTANEOUS the given set of
REACTION? conditions is
called a
spontaneous
reaction.
If a reaction does
not occur under
WHAT IS
NON- specified
SPONTANEOUS
conditions , it is
REACTION?
said to be
nonspontaneous.
Tell whether the
following is
spontaneous and
nonspontaneous.
A waterfall runs downhill.
Tell whether
the following
is spontaneous
and
nonspontaneou
s.
Tell whether the
following is
spontaneous and
nonspontaneous.
Ice melts above 0 degree
Celsius.
Tell whether the
following is
spontaneous and
nonspontaneous.
Heat flows from colder
object to hotter one.
Tell whether the
following is
spontaneous and
nonspontaneous.
Gathering all gas
molecules into one bulb.
Tell whether the
following is
spontaneous and
nonspontaneous.
Iron exposed to water and
oxygen to form rust.
Second Law of Thermodynamics
ENTROPY

● Entropy, S, is a thermodynamic
quantity.
● it is used to measure how spread
out or dispersed the energy of a
system is.
● it is used to describe if the
process is spontaneous and can
occur in a defined direction or
non-spontaneous that occur in
the reverse direction.
Entropy – quantitative measure of disorder
18
ENTROPY

● It is also considered as a state


function.

● It is also measure how random or


disorder the system is.
PROCESSES THAT LEAD TO AN
INCREASE IN ENTROPY OF THE
SYSTEM:

● MELTING
● VAPORIZATION
● DISSOLVING
● HEATING
MELTING
VAPORIZATION
DISSOLVING
HEATING
HOW WILL
YOU
PREDICT
WHEN
ENTROPY
IS
POSITIVE
OR
NEGATIVE
?
DETERMINE THE ENTROPY OF A SYSTEM FOR
EACH OF THE FOLLOWING PROCESSES.
1. A solid melts.
2. A liquid freezes.
3. A vapor is converted to a solid.
4. A vapor condenses to a liquid
5. A solid sublimes
DETERMINE THE ENTROPY OF A SYSTEM FOR
EACH OF THE FOLLOWING PROCESSES.
6.
DETERMINE THE ENTROPY OF A SYSTEM FOR
EACH OF THE FOLLOWING PROCESSES.
DETERMINE THE ENTROPY OF A SYSTEM FOR
EACH OF THE FOLLOWING PROCESSES.
DETERMINE THE ENTROPY OF A SYSTEM FOR
EACH OF THE FOLLOWING PROCESSES.
DETERMINE THE ENTROPY OF A SYSTEM FOR
EACH OF THE FOLLOWING PROCESSES.
Solving for Standard Values of
Entropy

or
Another thermodynamic
property that is used to
predict whether the
WHAT reaction or process will
IS be spontaneous or
GIBBS nonspontaneous.
FREE
ENERGY It can be calculated using
? the table of standard
values.
WHAT
IS
GIBBS
FREE
ENERGY
?
WHAT
IS
GIBBS
FREE
ENERGY
?
Example: Calculate the
and for the
reaction at 25
degree Celsius.
Example: In order to get the
Gibbs Free Energy,
Get the enthalpy and
entropy of the given
chemical equation.
After getting the
enthalpy and
entropy, substitute it
to the formula of
Gibbs Energy.
Another thermodynamic
property that is used to
predict whether the
WHAT reaction or process will
IS be spontaneous or
GIBBS nonspontaneous.
FREE
ENERGY It can be calculated using
? the table of standard
values.

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