Chapter 9 - Oxidization-Reduction Reactions Flashcards
what is an important characteristic in many reactions?
electron transfer
when reactions transfer electrons, what 3 characteristics do they have?
one entity gains electrons, one entity loses electrons, total number of electrons gained and lost are equal
define oxidation
the process by which one or more electrons is lost by a chemical entity
define reduction
the process in which one or more electrons is gained by a chemical entity
define oxidation-reduction reaction
the reaction in which one or more electrons are transferred between chemical entities
what is another word for oxidation-reduction reaction
redox reaction
what form is the total ionic equation in?
spectator ions are included and all aqueous solutions are written as dissociated ions
what form is the total ionic equation in?
write total ionic equation and remove spectator ions
define half-reaction equation
the part of an oxidation-reduction reaction equation representing either the oxidation or the reduction reaction
define oxidation number
a number used to keep track of electrons in oxidation-reduction reactions according to certain rules
what is oxidation number also known as?
oxidation state
what is the proper definition of oxidation number
the apparent net electric charge an atom would have if electron pairs in covalent bonds belonged entirely to the more electronegative atom and the shared electrons were divided equally between identical atoms
what does the oxidation number not actually represent?
the actual charge on the atom
two rules for assigning oxidation numbers
sum of oxidation numbers of all atoms in an electrically neutral compound must equal zero (zero sum rule), sum of oxidation numbers of all atoms in ions containing two or more atoms must equal the overall charge of the ion
oxidation number of a monatomic ion
same as the charge on the ion
oxidation number of an atom in its element
0
oxidation number of fluorine in its compounds
-1
oxidation number of oxygen in its compounds
-2, but -1 in peroxides, when there are two oxygens bonded
oxidation number of hydrogen in its compounds
+1 in covalent compounds, but -1 in metal hydrides (hydrogen and a metal)
convention when writing oxidation numbers vs actual charges
actual charges put number then sign, in oxidation numbers, write sign and then number
what can electrons do in redox reactions?
direct transfer of electrons from one reactant to another or partial transfer in covalent bonds where they shift towards the more electronegative element
define oxidization agent
the reactant that is reduced (gains electrons from another substance) and causes oxidization during an oxidation-reduction reaction
define reducing agent
the reactant that is oxidized (loses electrons to another substance), and causes reduction during an oxidation-reduction reaction
how do we name the reducing/oxidation agent?
specify the whole substance, and not just the element that is oxidized/reduced
why do oxidation and reduction reactions have to occur in the same reaction?
during a reaction where an entity is oxidized, the entity loses electrons, represented by oxidation half-reaction, the electrons lost are transferred to another entity, which gains the electrons and becomes reduced, represented b reduction half-reaction, since electrons are exchanged from one half-reaction to the other, both have to occur in the same reaction
two ways to balance redox reactions
oxidation numbers method or half-reactions method
how do we know a redox reaction has occurred?
if there is a change in the number of oxidation numbers of atoms from the reactant side to the product side
where do redox reactions take place and what 2 things does this mean
in aqueous solutions, water molecules may participate, may be acidic, neutral or basic
what happens if a redox reaction occurs in acidic solution
H+ (aq) may be participants
what happens if a redox reaction occurs in a basic solution
OH- (aq) may be participant
