redox Flashcards
oxidation number: number assigned to_____________ to show _________________________
element, state of oxidation
RULES
oxidation number of a monoatomic ion is
equal to charge of ion
RULES
oxidation number of grp 1 elements
+1 always
RULES
oxidation number of grp 2 elements
+2 alwayss
RULES
oxidation number of atom in elemental (free/combined) state is
0
RULES
oxidation number of grp 13 elements
+3 alwaaaays
RULES
in neutral compound, sum of oxidation nos=
0
RULES
oxidation number of H
- +1 mostly
- -1 in METAL HYDRIDES (smth combined w a metal)
RULES
oxidation number of O
- -2 mostly
- -1 in PEROXIDES
- +2 in OF2
RULES
oxidation number of F
-1 always
RULES
in polyatomic ion, sum of all oxidation states of all constituent atoms =
charge of ion
OXIDATION is the
- GAIN in oxygen
- LOSS of hydrogen
- INCREASE in OXIDATION NO
- LOSS of electrons (+ charge)
REDUCTION is the
- LOSS of oxygen
- GAIN in hydrogen
- DECREASE in OXIDATION NO
- GAIN of electrons (- charge)
Oxidation: process involving:
reduction: process involving:
eg: Mg + CuO —> MgO + Cu
- gain in oxygen
- loss of oxygen
Oxidation: process involving
reduction: process involving
eg: Cl2 + N2H2 —> N2 + 2HCl
- loss of hydrogen
- gain in hydrogen
CHANGE IN OXIDATION NO (most impt)
increase:
decrease:
- oxidation
- reduction
def: ______________ is a process in which oxidation no. of a _______________ increases
oxidation, substance
def: _______________ is a process in which oxidation no. of a _____________ decreases
reduction, substance
answer format:
Oxidation no. of X increases from 0 in X to +1 in XZ. hence X is ___________
oxidised
how to find change in oxidation no:
- write oxidation state of every __________ in every substance in the ________ eqn
- compare oxidation states of the ______ elements ________ & ________ reaction
- if increase:____________, if decrease:____________
- element, ionic
- same, b4, after
- oxidation, reduction
answer format:
oxidation no of X decreases from +2 in AX to 0 in X. hence X is _____________
reduced
HALF EQUATIONS:
eg
oxidation: Mg —> Mg2+ + 2e-
reduction: Zn2+ + 2e- —> Zn
- loss of electrons (oxidation): _____ hand side
- gain of electrons (reduction): _____ hand side
- right
- left
GAIN/LOSS OF ELECTRONS
oxidation: ______ of electrons
reduction: ______ of electrons
- loss
- gain
METHOD for half eqns
- identify species being oxidised/reduced
- balance no. of _______ on each side of eqn
- balance overall charge by __________ electrons
- atoms
- adding
CRITERIA for half eqns
1. no. of _______ of each element must be ________ on both sides of eqn
2. overall charge must be ________ on both sides
- atoms, equal
- equal
REDOX REACTION
def: ____________ __________ reactions where _______ oxidation and reduction occur ______________________
electron transfer, both, simultaneously
REDOX REACTION
ans format:
oxidation state of X decreases from 0 in X to -1 in XB. hence X is _________
oxidation state of Y increases from -1 in YT to 0 in Y. hence Y is _________
since _________&_________ occurs ___________________, it is a ________ reaction
- reduced
- oxidised
- oxidation, reduction, simultaneously, redox
DISPROPORTIONATION REACTIONS
def: _______ reaction in which a ______ ____________ undergoes oxidation & reduction _____________________
redox, single substance, simultaneously
DISPROPORTIONATION REACTIONS
ans format:
oxidation state of Y increases from 0 in Y to +2 in YL. hence Y is ____________
oxidation state of Y decreases from 0 in Y to -1 in YO. hence Y is __________
since Y is both oxidised & reduced ___________________, it is a _______________________ reaction
- oxidised
- reduced
- simultaneously, disproportionation
Oxidising agent: ___________ that __________ other substances but itself undergoes ______________
substance, oxidises, reduction
Reducing agent: ____________ that __________ other substances but itself undergoes ____________
substance, reduces, oxidation
eg of OXIDISING AGENT: KMnO4
colour change: ________ to _________________ (cus of Mn2+ formed)
purple —> colourless
eg of REDUCING AGENT: KI
colour change: ____________ to ________(cus of I3- formed)
colourless—>brown
