REDOX reactions Flashcards
what is a redox reaction
one which involves both oxidation and reduction as electrons are transferred between two species and changes in oxidation numbers are observed
Name 2 common redox rxns
corrosion and combustion
Define oxidation
-the loss of electrons
-an increase in oxidation #
-the loss of hydrogen
-the gain of oxygen
Define reduction
-the gain of electrons
- a decrease in ox#
- the gain of hydrogen
- the loss of oxygen
What is an oxidation number
A number assigned to an ion in an ionic compound or an atom in a molecule
For ions what is oxidation state
the number of electrons lost or gained when the ion is formed from its element
For atoms in covalent compounds what is oxidation state
the number of electrons that an atom partially gains or loses in a molecule
The oxidation number is +ve if…
Electrons are totally or partially lost
The oxidation number is -ve if…
Electrons are totally/partially gained
The oxidation number of uncombined elements is
0
the ox # of all atoms of an element in its free state is
0 eg. Cu=0
The ox# of elements that exist as simple ions in ionic compounds
is the same as the charge on the ion eg. in AlCl3: Al= +3 Cl=-1
the ox. # of elements in radicals or in covalent compnds
may vary. often appear in the name of the ion or compound
The sum of all ox # of elements in a compound is
zero eg. Al2O3 = 2(ox# of Al) + 3(ox# of O) =0
2(+3) + 3(-2) = 0
The sum of all ox # of elements in a radical is equal to the charge on the ion
eg. SO4 ²−
ox# of S + 4(-2) = -2
S = +6
