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50 terms

Chemistry Module #16-FINAL CHAPTER

For Chemistry with Mrs.Weeks at TPS
STUDY
PLAY
Oxidation Number
The charge that an atom in a molecule would develop if the most electronegative atoms in the molecule took the shared electrons from the less electronegative atoms
Oxidation numbers treat all compounds as
ionic
Oxidation numbers
aren't real
Oxidation numbers do not
have any significance in the real world
The sum of all oxidation numbers
in a molecule must equal the charge of that molecule
Rule #1
When a substance has only one type of atom, the oxidation number for that atom = the charge of the substance divided by the number of atoms present
Rule #2
Group 1A metals always have a +1 O. # in molecules that have more than 1 type of atom
Rule #3
Group 2A metals always have a +2 O. # in molecules that have more than 1 type of atom
Rule #4
Fluorine always has a -1 O. # in molecules that have more than 1 type of atom
Rule #5a
When with 1 other atom that is a metal, H has a -1 O. #
Rule #5b
When with other multiple atoms, H has a +1 O. #
Rule #6
Oxygen has an -2 O.# in molecules that have more than 1 type of atom
Rule #7
If all else fails, apply the O. # as the same as what the atom would take in an ionic compound. Groups 3A, 6A and 7A work best.
Oxidation
the process by which an atom loses electrons
Reduction
the process by which an atom gains electrons
LEO says GER
lose electrons oxidation, gain electrons reduction
when an atom undergoes reduction
we say that it has been reduced
when an atom undergoes oxidation
we say that it has been oxidized
If any 2 atoms change oxidation numbers in a reaction
it is a redox reaction
Electricity
is just electrons traveling through a wire
voltmeter
indicates the voltage of a battery
salt bridge
cancels out + or - charge that develops in an anode or cathode
a salt bridge contains
an aqeuous ionic compound and is necessary for the proper working of the battery
anode
negative side of the battery
cathode
positive side of the battery
anions
negative ions
cation
source of positive charges
galvanic cell
battery as described in Module 16
metal strips conducting electrons
electrodes
Lead-acid battery
car battery
in lead acid battery, reactants
PbO2, Pb and H2SO4 (aq)
in lead acid battery, products
PbSO4, H2O
when you recharge a battery,
you reverse the reaction, converting produscts to reactant
dry cell battery
contains no aqueous solutions
dry cell battery used in flashlights
alkaline cell because the salt bridge uses KOH, a base
in alkaline batteries, the inner construction of the battery is broken down
which means it can not recharge
redox reactions are often useful,
but can be harmful (rust, corrosion)
corrosion is
oxidation
use the 7 rules of determining ox. numbers as a
hierarchy
what happened in exp. 16.1
citric acid oxidized iodine to 5+ in order to form the blue starch compound, it needed to be 0
anodes go on the
left
cathodes go on the
right
car battery is
rechargeable
dry cell battery
no aq solution
the anode must be made of
metal in equation
cathode does not need to be made of
metal in equation
cations
+ ions
anions
- ions
all batteries are not
galvanic cells
h2so4 is a reactant
in a lead acid battery