Regents Warm-Up
Which two characteristics are associated with
metals?
(1) low first ionization energy and low
electronegativity
(2) low first ionization energy and high
electronegativity
(3) high first ionization energy and low
ENTROPY
AIM:
What is ENTROPY?
DO NOW:
What are the oxidation #s in
1) HOBr
2) KClO3
ENTROPY
• ENTROPY (DS): a
measure of the
randomness or disorder
in a system.
• A system with more
disorder has a greater
entropy
• What are some examples
of entropy?
ENTROPY
• Phase changes are
changes in the entropy
of the molecules
• solidliquidgas
------ENTROPY
• Entropy increases as
disorder of molecules
increases
ENTROPY
• Changes occur so the
• For a reaction, when the
highest possible entropy
amt of gas being produced
is reached.
h the overall entropy will
• Increases in entropy favor
h
SPONTANEOUS RXNS
• Example:
• Does dissolving a gas in a
SO3(g)  2SO2(g) + O2(g)
liquid (soda) increase or
decrease entropy?
• Solutions h in entropy
when something is added
This causes a i in entropy
• h in temp will h entropy
ENTROPY
Which sample has the
greatest entropy?
1. NH3(g)
2. NH3(s)
3. NH3(l)
4. NH3(aq)
Which process is
accompanied by a
decrease in entropy?
1. boiling of water
2. subliming of iodine
3. condensing of water vapor
4. melting of ice
ENTROPY
•
Entropy h when:
1.
2.
3.
4.
a solid becomes a gas
a solid becomes a liquid
a liquid becomes a gas
Something is broken
into smaller pieces
• In our bodies the desire to
become disordered is
counteracted by all the
energy and heat we
produce
• Therefore, changes in
entropy(DS) and enthalpy
(DH) can tell us if a
reaction will be
spontaneous
ENTROPY
• A system tends to
change toward lower
enthalphy and higher
entropy
• Spontaneous reactions
occur naturally and
favor product
formation
• Some reactions may depend
on conditions for example:
C6H12O6(s) CO2(g)+H2O(g)
• Some endothermic reactions
are spontaneous due to an h in
entropy (ex. ice melting)
• h in entropy favors
spontaneous reactions
ENTROPY
As carbon dioxide
sublimes, its entropy
Which sample has the
lowest entropy?
1. decreases
2. Increases
3. remains the same
1.
2.
3.
4.
KNO3(l)
KNO3(s)
H2O(l)
H2O(g)
ENTROPY
At STP, a sample of
which element has the
highest entropy?
1. Na(s)
2. Br2(l)
3. Hg(l)
4. F2(g)
Which list of the phases of
H2O is arranged in order
of increasing entropy?
1. ice, steam, and liquid
water
2. steam, liquid water, and
ice
3. ice, liquid water, and
steam
4. steam, ice, and liquid
water