redox

Question 1

oxidation number: number assigned to_____________ to show _________________________

Answer 1

element, state of oxidation

Question 2

RULES
oxidation number of a monoatomic ion is

Answer 2

equal to charge of ion

Question 2

RULES
oxidation number of grp 1 elements

Answer 2

+1 always

Question 2

RULES
oxidation number of grp 2 elements

Answer 2

+2 alwayss

Question 2

RULES
oxidation number of atom in elemental (free/combined) state is

Answer 2

0

Question 2

RULES
oxidation number of grp 13 elements

Answer 2

+3 alwaaaays

Question 3

RULES
in neutral compound, sum of oxidation nos=

Answer 3

0

Question 3

RULES
oxidation number of H

Answer 3

• +1 mostly
• -1 in METAL HYDRIDES (smth combined w a metal)

Question 3

RULES
oxidation number of O

Answer 3

• -2 mostly
• -1 in PEROXIDES
• +2 in OF2

Question 3

RULES
oxidation number of F

Answer 3

-1 always

Question 4

RULES
in polyatomic ion, sum of all oxidation states of all constituent atoms =

Answer 4

charge of ion

Question 5

OXIDATION is the

Answer 5

• GAIN in oxygen
• LOSS of hydrogen
• INCREASE in OXIDATION NO
• LOSS of electrons (+ charge)

Question 6

REDUCTION is the

Answer 6

• LOSS of oxygen
• GAIN in hydrogen
• DECREASE in OXIDATION NO
• GAIN of electrons (- charge)

Question 7

Oxidation: process involving:
reduction: process involving:
eg: Mg + CuO —> MgO + Cu

Answer 7

• gain in oxygen
• loss of oxygen

Question 8

Oxidation: process involving
reduction: process involving
eg: Cl2 + N2H2 —> N2 + 2HCl

Answer 8

• loss of hydrogen
• gain in hydrogen

Question 8

CHANGE IN OXIDATION NO (most impt)
increase:
decrease:

Answer 8

• oxidation
• reduction

Question 9

def: ______________ is a process in which oxidation no. of a _______________ increases

Answer 9

oxidation, substance

Question 10

def: _______________ is a process in which oxidation no. of a _____________ decreases

Answer 10

reduction, substance

Question 11

answer format:
Oxidation no. of X increases from 0 in X to +1 in XZ. hence X is ___________

Answer 11

oxidised

Question 11

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:____________

Answer 11

• element, ionic
• same, b4, after
• oxidation, reduction

Question 12

answer format:
oxidation no of X decreases from +2 in AX to 0 in X. hence X is _____________

Answer 12

reduced

Question 12

HALF EQUATIONS:
eg
oxidation: Mg —> Mg2+ + 2e-
reduction: Zn2+ + 2e- —> Zn
- loss of electrons (oxidation): _____ hand side
- gain of electrons (reduction): _____ hand side

Answer 12

• right
• left

Question 13

GAIN/LOSS OF ELECTRONS
oxidation: ______ of electrons
reduction: ______ of electrons

Answer 13

• loss
• gain

Question 14

METHOD for half eqns
- identify species being oxidised/reduced
- balance no. of _______ on each side of eqn
- balance overall charge by __________ electrons

Answer 14

• atoms
• adding

Question 15

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

Answer 15

- atoms, equal - equal

Question 16

REDOX REACTION def: ____________ __________ reactions where _______ oxidation and reduction occur ______________________

Answer 16

electron transfer, both, simultaneously

Question 17

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

Answer 17

- reduced - oxidised - oxidation, reduction, simultaneously, redox

Question 18

DISPROPORTIONATION REACTIONS def: _______ reaction in which a ______ ____________ undergoes oxidation & reduction _____________________

Answer 18

redox, single substance, simultaneously

Question 19

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

Answer 19

- oxidised - reduced - simultaneously, disproportionation

Question 20

Oxidising agent: ___________ that __________ other substances but itself undergoes ______________

Answer 20

substance, oxidises, reduction

Question 21

Reducing agent: ____________ that __________ other substances but itself undergoes ____________

Answer 21

substance, reduces, oxidation

Question 22

eg of OXIDISING AGENT: KMnO4 colour change: ________ to _________________ (cus of Mn2+ formed)

Answer 22

purple —> colourless

Question 23

eg of REDUCING AGENT: KI colour change: ____________ to ________(cus of I3- formed)

Answer 23

colourless—>brown