redox

Question 1

define redox

Answer 1

reduction, oxidation
reaction occur together

smth must oxidise, smth must reduce

oxidise: individual element’s O.S. increases LHS -> RHS
reduces: individual element O.S. decreases LHS -> RHS

Question 2

oxidation state vs oxidation number in olvl

Answer 2

same thing

Question 3

any element oxidation state

Answer 3

always 0

ELEMENT HAVE NO CHARGE.

Question 4

any ion oxidation state

Answer 4

charge, ion

i.e. Iron (II) oxidation state: +2
i.e. X 3- oxidation state -3

Question 5

1 unit oxygen oxidation state (bonded 2 compound)

Answer 5

O: -2

EXCEPT FOR
hydrogen peroxide’s oxygen (H2O2): -1

i.e. Na2 O

Na: +1
Na2: +2
O: -2

O.S.: +2-2 = 0

Question 6

1 unit hydrogen oxidation state (bonded 2 nonmetal)

Answer 6

+1

Question 7

1 unit hydrogen oxidation state (bonded 2 metal)

Answer 7

-1

Question 8

total oxidation state of compound

Answer 8

add up to Zero

Question 9

total oxidation state of: OH-
NO3 2-
SO4 2-
CO3 2-
NH4 +

Answer 9

total oxidation state = charge

i.e.
SO4 2- total oxidation state: -2

1 unit O oxidation state: -2
4 unit O oxidation state: -8

Therefore, sulfur oxidation state: +6

Question 10

does molar number (big number) affect oxidation state?

Answer 10

no

Question 11

to find oxidation/reduction of X3 + y2 = y2x3 , look for:

X3’s OS or X’s OS?

Answer 11

X’s OS

look for it individual to compare (standardized)

Question 12

to find out which oxidate, reduce, what to find?

Answer 12

1. find O.S., all other element beside oxygen

Question 13

O.S. of X (LHS) in XY > +2
O.S. of X(RHS) in XY > +3

Did X oxidise, or reduce?

Answer 13

1. X in XY oxidised
2. Oxidation State of X increases from +2 to +3 in XY

Question 14

XY individual O.S. of Y (LHS) > 2-
XY individual O.S. of Y (RHS) > 3-
is Y

Answer 14

1. Y in XY reduced
2. Oxidation State of Y decreases from 2- to 3- in XY

Question 15

most of time how to tell if not redox?

Answer 15

GUIDE, DONT WRITE IN EXAM!!
no free element

what is a free element
i.e. 2Fe, Cl2, Cr2

what is not a free element
i.e. Co3 2-, HNO3 -, Co2

Question 16

shoe

4 definition of oxidation

Answer 16

SHOE

State - o.s. increase
Hydrogen - lose hydrogen
Oxygen - gain oxygen
Electron - lose electron

Question 17

effect of oxidising agent on X

Answer 17

X -> oxidised
oxidising agent -> reduced

Question 18

test for reducing agent

Answer 18

R: acidified KMno4 purple -> colourless

Question 19

example of Oxidising agent

Answer 19

acidified potassium maganate(VII) KMnO4

Question 20

example of reducing agent

Answer 20

potassium iodide solution
KI

Question 21

test for oxidizing agent

Answer 21

R: potassium iodide soln. colourless -> brown

Question 22

bromine maganate (III)

Which part does “III” belong to?

Answer 22

(III) belongs to Maganate

Question 23

is hydrogen peroxide oxidising or reducing agent?

Answer 23

can act as BOTH

Question 24

other oxidising agent beside Kmno4

other reducing agent beside KI

Answer 24

oxidising agent: Acidified potassium dichromate (K2Cr2O7)
reducing agent: aq iron (II) ion

Question 25

dispropornation v comproportionation

Answer 25

**both are redox** dispropornation: 1 reactant -> 2 product comproportionation: 2 reactant -> 1 product

Question 26

so2 (g) is a...

Answer 26

reducing and oxidising agent

Question 27

grp1, grp17 which is good reducing/oxidising agent?

Answer 27

g1->good reducing agent g17 ->good oxidising agent

Question 28

neutralisation is redox?

Answer 28

no