Transcript Slide 1

Redox Reactions
I. Oxidation & Reduction -_________-_________
oxidation reduction ________,
reactions or
_____
redox ________,
reactions are ________
reactions in which
________
electrons are __________
transferred from one
atom
another atom
____ to _______
____
2Na (s)
+
1Cl2 (g)
Synthesis
2NaCl (s)
+
Na
Cl
Cl
Na
+
Cl
Na
-
Cl
+
Na
-when _______
Sodium reacts with Chlorine
_______,
each Sodium
______ _____
___
atom ________
transfers one
_______
electron to a _______
Chlorine _____
atom
2Na (s)
+
1Cl2 (g)
-
2Na1+ + 2Cl1-
Redox Reactions
I. Oxidation & Reduction -_________
oxidation is defined as the ____
loss of
________
_____ of a ________
electrons from the atoms
substance
-during its reaction with Chlorine
_______, Sodium
______
_____
loses ________:
electrons
oxidation number is
equal to the number
of electrons lost or
gained by an atom
Reduction causes
the numerical value
of the oxidation number
to be reduced
Oxidation causes
the numerical value
of the oxidation number
to increase
0
oxidized
+1
Na
Na1+ + eSodium is ________
oxidized
-_______
reduction is defined as the gain
-_________
____ of
electrons by the _____
atoms of a ________
substance
________
Sodium
-during its reaction with _______,
Chlorine _____
gains ________:
electrons
________
0
Cl2 +
2e-
reduced
-________
Chlorine is _______
reduced
-1
2Cl1-
Redox Reactions
I. Oxidation & Reduction -a substance which ________
oxidizes another
substance by ________
accepting its ________
electrons is
called an ________
oxidizing _____,
agent which is also
reduced
the substance that is _______
-a substance which _______
reduces another
substance by ______
losing ________
electrons is
reducing _____,
agent which is also
called an ________
oxidized
the substance that is ________
oxidized
2K (s) + 1Br2 (g)
2KBr (s)
reduced
covalent compounds
partially
-________
_________ become _______
________
oxidized and _______
partially _______
reduced by
the _______
unequal _______
sharing of ________;
electrons the
more _____________
electronegative is considered to be
reduced and the less _____________
electronegative is
_______
oxidized
considered to be ________
Redox Reactions
I. Oxidation & Reduction
oxidized
3H2 (g) +
1N2 (g)
2NH3 (g)
reduced
Identify each of the following changes as oxidation or reduction:
I2
K
0
+
0
2e-
oxidized
+2
-1
reduced
2I1-
Fe2+
+1
K1+
oxidized
+1
+
e-
Ag1+
+
e-
+3
Fe3+ + ereduced
Ag
Identify what is oxidized and what is reduced in each of the following:
2Br1- + 1Cl2
1Br2 + 2Cl1oxidized
reduced
2Ce + 3Cu2+
oxidized
reduced
2Zn + 1O2
oxidized
3Cu + 2Ce3+
reduced
2ZnO
0
Redox Reactions
I. Oxidation & Reduction
Identify the oxidizing agent and the reducing agent in each of the
following reactions:
1Mg + 1I2
reducing
agent
oxidizing
agent
2Na + 2H1+
reducing
agent
1MgI2
1H2 + 2Na1+
oxidizing
agent
1H2S + 1Cl2
reducing
agent
oxidizing
agent
1S
+ 2HCl
Redox Reactions
I. Oxidation & Reduction
Determine the oxidation number of the boldface element in each of the
chemical formulas below:
+1+ 1(x) + 4(-2) = 0
NaClO4
+7
NH4Cl
-3
Ca3N2
MgB4O7
-3
+3
AlPO4
+5
Li3AsO4
+5
HIO4
+7
Fe2O3
+3
HNO2
+3
K2CrO4
+6
KMnO4
+7
HNO3
+5
Redox Reactions
I. Oxidation & Reduction
Determine the oxidation number of the boldface element in each of the
polyatomic ions below:
1(x) + 4(+1) = +1
NH41+
AsO43-
CrO42-
-3
+5
+6
+7
B4O72-
NH21-
ClO41-
+3
-3
+7
SO42-
NO21-
+6
+3
MnO41+7
ClO31+5
IO41-
CO32+4
Redox Reactions
II. Balancing Redox Equations
Use the oxidation-number method to balance the redox equation below:
Cu (s) + HNO3 (aq)
Cu(NO3)2 (aq) + NO2 (g)
+ H2O (l)
1. Assign oxidation numbers to all atoms in the equation.
0
Cu (s) +
+1 +5 -2
+2
+5 -2
HNO3 (aq)
Cu(NO3)2 (aq) +
+4 -2
+1
-2
NO2 (g) +
H2O (l)
2. Identify the atoms that are oxidized and the atoms that are reduced.
oxidized
0
Cu (s) +
+1 +5 -2
HNO3 (aq)
+2
+5 -2
Cu(NO3)2 (aq) +
reduced
+4 -2
+1
-2
NO2 (g) +
H2O (l)
Redox Reactions
II. Balancing Redox Equations
3. Determine the change in oxidation number for the atoms that are
oxidized and for the atoms that are reduced.
+2
oxidized
0
Cu (s) +
+1 +5 -2
+2
HNO3 (aq)
+5 -2
Cu(NO3)2 (aq) +
+4 -2
+1
-2
NO2 (g) +
H2O (l)
reduced
-1
4. Make the change in oxidation numbers equal in magnitude by
adjusting coefficients in the equation.
+2
oxidized
0
Cu (s) +
+1 +5 -2
HNO3 (aq)
+2
+5 -2
+4 -2
Cu(NO3)2 (aq) + 2 NO2 (g) +
reduced
-1(2) = -2
+1
-2
H2O (l)
5. If necessary, use the conventional method to balance the remainder of
the equation.
+2
oxidized
0
+1 +5 -2
+2
1 Cu (s) + 4 HNO3 (aq)
+5 -2
+4 -2
+1
-2
1 Cu(NO3)2 (aq) + 2 NO2 (g) + 2 H2O (l)
reduced
-1(2) = -2
Use the oxidation-number method to balance the redox equations below:
+2 (3) = +6
+1 -1
3 HCl
+1 +5 -2
+
+1 -2 +1
2 HNO3
3 HOCl
+2 -2
+ 2 NO
-3 (2) = -6
+3 (2) = +6
3 SnCl4 +
2 Fe
3 SnCl2
+ 2 FeCl3
-2 (3) = -6
+3 (4) = +12
8 4 NH3 (g) + 6 3 NO2 (g)
-4 (3) = -12
7 N2 (g) + 12 H2O (l)
+1
-2
+ 1 H2O
Redox Reactions
II. Balancing Redox Equations
Al (s) +
NH4ClO4 (s)
Al2O3 (g) + HCl (g) + N2 (g) + H2O (g)
Use the oxidation-number method to balance the equation:
0
-3 +1
Al (s) +
+7 -2
NH4ClO4 (s)
oxidized
+3
-2
+1 -1
0
+1
-2
Al2O3 (g) + HCl (g) + N2 (g) + H2O (g)
+3
+3
oxidized
reduced -8 (3) = -24
The _____
space ______
shuttle gains nearly ____
72%
of its ___
lift from its _____
solid ______
rocket
_______
boosters (_____)
SRB’s during the ____
first ___
two
minutes of ______.
launch The ______
SRB’s
_______
contain _______
495,000 ___
kg of a
each _______
_______
mixture of __________
Aluminum and
___________
Ammonium __________
perchlorate
http://alanrider.files.wordpress.com/2009/01/space_shuttle_launch.jpg
Redox Reactions
II. Balancing Redox Equations
10 Al(s)+ 6 3 NH4ClO4 (s)
oxidized
+3
5 Al2O3 (g) + 6 HCl (g) + 3 N2 (g) + 9 H2O (g)
+3
oxidized
reduced -8 (3) = -24
While in _____
orbit the _____
space _______
shuttle uses
a ___________
spontaneous __________
propulsion _______
reaction to
________,
maneuver which involves
___________________
monomethylhydrazine as the
propellant and __________
Dinitrogen _________
tetroxide
_________
as the_______
oxidizer
https://secure.reservexl.net/wwwimg/img/tours/38-2.jpg
Redox Reactions
II. Balancing Redox Equations
N2O4
+
CH3N2H3
CO2
+
N2 +
H2O
Use the oxidation-number method to balance the equation:
+4 -2
-4 +1 -1 +1
+4 -2
0
+1 -2
4
4
9
12
5 2 N2O4
2 1 CO2 + 4 2 N2 + 6 H2O
+ 2 1 CH3N2H3
oxidized +8
oxidized +1
reduced
-4 (2) = -8
http://www.arcadiastreet.com/cgvistas/spacexp/images/se_spaceshuttle_orbit_insert_600.jpg
Redox Reactions
II. Balancing Redox Equations
Use the oxidation-number method to balance the following equations:
HClO3 (aq)
ClO2 (g) + HClO4 (aq) + H2O (l)
H2O2 (aq) +
H2SO4 (aq) + FeSO4 (aq)
H2SeO3 (aq)
+
HClO3 (aq)
Fe2(SO4)3 (aq) + H2O (1)
H2SeO4 (aq) + Cl2 (g) + H2O (l)
Redox Reactions
II. Balancing Redox Equations
1. Hypothesis: How do you know if an oxidation-reduction reaction has
occurred?
2. Prediction:
3. Gather Data:
A. Safety: Copper(II) sulfate is mildly toxic, with an LD50 =
300mg/kg. Avoid ingestion (don’t eat or drink it).
Wash hands thoroughly with soap and water before
leaving lab. Goggles mandatory. Copper(II) sulfate is
an environmental hazard, being extremely toxic to
aquatic organisms like algae.
B. Procedure:
1. Use a piece of sandpaper to polish the end of an iron nail.
3. Gather Data:
B. Procedure:
2. Add about 3 mL of 1.0 M CuSO4 solution to a test tube.
3. Place the polished end of the nail in the CuSO4 solution.
Let stand and observe for about 10 minutes. Record your
observations. ___________________________________
4. Analyze Data:
1. What is the substance found clinging to the nail? _______
2. What happened to the color of the CuSO4 solution? _____
______________________________________________
3. Write the balanced chemical equation for the reaction you
observed: ______________________________________
4. What substance was oxidized? _____________________
5. What substance was reduced? _____________________
Redox Reactions
III. Half-Reactions -in the _________-_________
oxidation reduction _______
reaction
___
____
______,
2Fe + 3Cl
2FeCl3 each ____
iron
2
_____
________
atom is ________
oxidized by ______
losing __
3 electrons
oxidation ____-_______
half reaction is:
-the _________
Fe
Fe3+ + 3e-each ________
________ is _______
chlorine molecule
reduced by
gaining __
2 ________
electrons
_______
reduction ____-_______
half reaction is:
-the _________
Cl2 + 2e-
2Cl-
Redox Reactions
III. Half-Reactions-in the _________-_________
oxidation reduction _______
reaction
___
________
Cu + _______
AgNO3
Cu(NO3)2 + ___,
Ag
each copper
______ _____
atom is ________
oxidized by ______
losing __
2
________
electrons
-the _________
oxidation ____-_______
half reaction is:
Cu2+ + 2esilver ____
ion is _______
reduced by _______
gaining __
1
-each ______
electron
________
Cu
reduction ____-_______
half reaction is:
-the _________
Ag1+ + 1e-
Ag
Redox Reactions
III. Half-Reactions
Write the oxidation and reduction half-reactions for the following
oxidation-reduction equations:
0
+2
Pb (s) +
Pd(NO3)2 (aq)
Pd2+ + 2e-
+5 -2
0
Pb(NO3)2 (aq) + Pd (s)
Pd
-2
KMnO4 (aq) +
SO2
+2
Pb2+ + 2e-
Pb
+1 +7
+5 -2
+4 -2
+1 +6 -2
SO2 (g)
K2SO4 (aq)
SO42- + 2e-
MnO41- + 5e-
Mn2+
+2
+6 -2
+ MnSO4 (aq)
Redox Reactions
III. Half-Reactions
Write the oxidation and reduction half-reactions for the following
oxidation-reduction equations:
+2
-2
-3 +1
PbO (s) +
0
NH3 (g)
PbO + 2e+2
+1
-2
N2 (g) + Pb (s) + H2O (l)
N2 + 6e-
2NH3
+1
0
-2
Pb
0
+1
Na2S2O3 (aq) + I2 (s)
S2O32I2 + 2e-
S2O422I1-
+3 -2
+1
-1
Na2S2O4 (aq) + NaI (aq)
+ 2e-
Redox Reactions
III. Half-Reactions
Write the oxidation and reduction half-reactions for the following
oxidation-reduction equations:
+1 -2 +1
+4 -2
+1 +3 -2
NaOH (aq) +
NO2 (g)
NaNO2 (aq) + NaNO3 (aq) + H2O (l)
NO2
NO31-
NO2 + 1e+1 -1
+ 1e-
NO210
+2
HCl (aq)
+ Sn (s)
Sn
Sn2+ + 2e-
2H1+ + 2e-
+1 +5 -2
-1
0
SnCl2 (aq) + H2 (g)
H2
+1
-2
Redox Reactions
III. Half-Reactions
Write the oxidation and reduction half-reactions for the following
oxidation-reduction equations:
+1 +3 -2
+1 +5 -2
+1 +5 -2
H3PO3 (aq) +
HNO3 (aq)
H3PO4 (aq)
PO33-
PO43-
NO31+1 -1
+ 3e+1
NO (g)
-2
+ H2O (l)
NO
+7 -2
+1 -1
+2
-1
+1
-2
0
KCl (aq) + MnCl2 (aq) + H2O (l) + Cl2 (g)
Cl2 + 2e-
MnO41- + 5e-
+
+1
+ 2e-
HCl (aq) + KMnO4 (aq)
2Cl-
+2 -2
Mn2+