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

does molar number (big number) affect oxidation state?

Answer 8

no

Question 9

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

X3’s OS or X’s OS?

Answer 9

X’s OS

look for it individual to compare (standardized)

Question 10

most of time how to tell if not redox?

Answer 10

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 11

shoe

4 definition of oxidation

Answer 11

SHOE

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

Question 12

effect of oxidising agent on X

Answer 12

X -> oxidised
oxidising agent -> reduced

Question 13

test for reducing agent

Answer 13

R: acidified KMno4 purple -> colourless

Question 14

example of Oxidising agent

Answer 14

acidified potassium maganate(VII) KMnO4

Question 15

example of reducing agent

Answer 15

potassium iodide solution
KI

hydrogen also reducing agent

Question 16

test for oxidizing agent

Answer 16

R: potassium iodide soln. colourless -> brown

Question 17

bromine maganate (III)

Which part does “III” belong to?

Answer 17

(III) belongs to Maganate

Question 18

is hydrogen peroxide oxidising or reducing agent?

Answer 18

can act as BOTH

Question 19

other oxidising agent beside Kmno4

other reducing agent beside KI

Answer 19

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

o2 is also oxidising agent

Question 20

dispropornation v comproportionation

Answer 20

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

Question 21

so2 (g) is a…

Answer 21

reducing and oxidising agent

Question 22

grp1, grp17
which is good reducing/oxidising agent?

Answer 22

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

Question 23

non redox reactions
redox reaction

Answer 23

non redox
neutralisation
precipitation salt formation

redox
displacement

Question 24

oxidation, reduction format

Answer 24

(compound/element) is oxidised because its oxidation state increases from +/-/0 to +/-/0 in (compound/element)

Question 25

iron + oxygen reaction

Answer 25

iron (III) oxide

Question 26

oxidising, reducing agent test (gases)

Answer 26

filter paper, some KI/KMnO4 soln.

Question 27

what if KI test very pale? how to see if KI colourless -> brown?

Answer 27

add few drops of starch if KI oxidised, I2 (aq), will turn dark blue