Chapter 12 - Redox reactions

Question 1

define redox reaction

Answer 1

reaction where both oxidation and reduction takes place

Question 2

define oxidising agent

Answer 2

assists other substances to oxidise

Question 3

define reducing agent

Answer 3

assists other substances to reduce

Question 4

table for OXIdation

Answer 4

OXYgen (+)
OXYdising agent (+)
hydrogen (-)
electrons (-)

Question 5

common non redox reactions

Answer 5

• neutralisation
• decomposition
• double displacement

Question 6

common redox reactions

Answer 6

• single displacement
• combustion
• synthesis

Question 7

test for oxidising agent and observations

Answer 7

add aqueous potassium iodide
= potassium iodide turns from colourless to brown

Question 8

test for reducing agent and observations

Answer 8

add acidified potassium manganate
= acidified potassium manganate turns from purple to colourless

Question 9

examples of oxidising agents (4)

Answer 9

• acidified potassium manganate
• halogens
• oxygen
• acidified potassium dichromate

Question 10

examples of reducing agents (5)

Answer 10

• aqueous potassium iodide
• carbon monoxide
• carbon
• group one metals and hydrogen - sulfur dioxide

Question 11

examples of both oxidising and reducing agent

Answer 11

water and hydrogen peroxide

Question 12

observation when oxidising agent is being reduced

Answer 12

acidified purple potassium manganate turns colourless

Question 13

observation when reducing agent is being reduced

Answer 13

colourless potassium iodide turns brown

Question 14

element / compound rule for oxidation

Answer 14

0

Question 15

ion rule for oxidation

Answer 15

see charge of ion

Question 16

hydrogen rule for oxidation

Answer 16

+1

Question 17

oxygen rule for oxidation

Answer 17

-2

Question 18

transition metal rule for oxidation

Answer 18

see roman letter

Question 19

group 1 elements rule for oxidation

Answer 19

+1

Question 20

group 2 elements rule for oxidation

Answer 20

+2

Question 21

group 3 elements rule for oxidation

Answer 21

+3

Question 22

rules in calculating oxidation state

Answer 22

the total has to be zero and individual elements can be solved with the rules

Question 23

4 types of doing redox reactions

Answer 23

• oxygen transfer
• hydrogen transfer
• electrons transfer
• oxidation state

Question 24

explanation for oxidation in oxygen transfer

CuO + H2 = Cu + H2O

Answer 24

CuO + H2 = Cu + H2O
= hydrogen has become oxidised
= it gained oxygen to become water
= copper (ll) oxide is the oxidising agent

Question 25

explanation for oxidation hydrogen transfer 2HCl + F2 = 2HF + Cl2

Answer 25

2HCl + F2 = 2HF + Cl2 = hydrochloric acid has become oxidised = it lost hydrogen to become chlorine gas = fluorine is the oxidising agent

Question 26

explanation for oxidation electrons transfer Zn + Cu2+ = Zn2+ + Cu

Answer 26

Zn + Cu2+ = Zn2+ + Cu = zinc metal has been oxidised = it lost two electrons to become Zinc ion = copper ion is the oxidising agent

Question 27

explanation for oxidation oxidation state K + NaCl = KCl + Na

Answer 27

K + NaCl = KCl + Na = potassium has been oxidised = its oxidation state increased from o in K to +1 in KCl = sodium chloride is the oxidising agent

Question 28

explanation for reduction in oxygen transfer CuO + H2 = Cu + H2O

Answer 28

CuO + H2 = Cu + H2O = copper (ll) oxide has been reduced = it lost oxygen to become copper metal = hydrogen is the reducing agent

Question 29

explanation for reduction hydrogen transfer 2HCl + F2 = 2HF + Cl2

Answer 29

2HCl + F2 = 2HF + Cl2 = fluorine has been reduced = it gained hydrogen to become hydrogen fluoride = hydrochloric acid is the reducing agent

Question 30

explanation for reduction electrons transfer Zn + Cu2+ = Zn2+ + Cu

Answer 30

Zn + Cu2+ = Zn2+ + Cu = copper ion has been reduced = it gained 2 electrons to become copper metal = Zn is the reducing agent

Question 31

explanation for reduction oxidation K + NaCl = KCl + Na

Answer 31

K + NaCl = KCl + Na = Sodium chloride is being reduced = its Oxidising agent decreased from +1 in NaCl to 0 in Na = potassium is the reducing agent

Question 32

theory : how to test for reducing agent like SO2

Answer 32

use acidifies potassium manganate (Vll), place on a filter paper and if gas evolved turns purple potassium manganate (Vll) colourless, gas is sulfur dioxide

Question 33

theory : how do you test for oxidising agent like F2

Answer 33

use aqueous potassium iodide and bubble gas evolved through KI if it turns colourless potassium iodide brown, the gas is a halogen

Question 34

theory : explain how potassium iodide can be used to test for an oxidising agent

Answer 34

When colourless aqueous potassium iodide is added to added to an oxidising agent, it turns brown due to iodine solution produced