U2AoS1 - Redox Reactions

Question 1

What are Redox Reactions?

Answer 1

A reaction that involves the transfer of electrons.
Processes of oxidation and reduction

Question 2

What are the types of redox reactions?

Answer 2

• Addition/combination reaction
• Decomposition reaction
• Displacement reaction
• Combustion reaction

Question 3

What is an addition reaction?

Answer 3

A + B – C

Question 4

What is a decomposition reaction?

Answer 4

c - A + B

Question 5

What is a displacement reaction?

Answer 5

A + BC – B + AC

Question 6

What is oxidation?

Answer 6

Loss of electrons

Question 7

What is reduction?

Answer 7

Gain of electrons

Question 8

Half equation

Answer 8

electrons shown as either a product or reactant depending on oxidation or reduction

Question 9

Reductant

Answer 9

Substance that causes another to be reduced and itself oxidised

Question 10

Oxidant

Answer 10

Substance which causes another to be oxidised and itself reduced

Question 11

Overall balance equation

Answer 11

Shows products/reactants but not electrons

Question 12

Ionic equation

Answer 12

Two half equations written together
- no spectator ions
- must be balanced when two added together

Question 13

Conjugate redox pair

Answer 13

Pair differ by one or more electrons
Oxidised form written first

Question 14

Are ionic compounds formed through redox reactions?

Answer 14

Transfer of electrons hence, yes

Question 15

Covalent molecular compounds… are they redox?

Answer 15

• can be involved despite shared
• partial electron transfer, unequal sharing of electrons

Question 16

Oxidation numbers

Answer 16

determines if a redox reaction has occured

Question 17

Oxidation number increases

Answer 17

Oxidised

Question 18

Oxidation number decreases

Answer 18

Reduced

Question 19

Oxidation number of free elements

Answer 19

O

Question 20

Oxidation number of ionic compounds

Answer 20

Charge of the ion

Question 21

Polyatomic oxidation numbers

Answer 21

Sum is equal to the charge on the ion

Question 22

Oxygen and Hydrogen Numbers

Answer 22

usually, -2 and +1

Question 23

UNDER ACIDIC CONDITIONS

Answer 23

KOHES
- key elements
- oxygen balanced by water
- hydrogen by H+ ions
- electrons added
- states

Question 24

Overall ionic equations

Answer 24

• balance no.
• add half equations
• cancel species on both sides

Question 25

Reactivity of metals

Answer 25

A will only replace B if A is more reactive. A is oxidised and B is reduced

Question 26

Forwards Reaction

Answer 26

Reduction

Question 27

Backwards Reaction

Answer 27

Oxidisation

Question 28

Strong oxidants

Answer 28

accept electrons more readily

Question 29

Strong reductants

Answer 29

donate protons more readily

Question 30

What is a Galvanic Cell?

Answer 30

Converts chemical energy to electrical energy from spontaneous redox reactions taking place in the cell

Question 31

What is a laboratory galvanic cell?

Answer 31

Reactants separated into half cells connected with wire and a salt bridge to complete the circuit and allow for movement of electrons

Question 32

Half cells

Answer 32

contains a conjugate redox pair, electrodes must conduct electricity

Question 33

Anode

Answer 33

negative polarity (oxidation) will decrease mass and increase color intensity

Question 34

Cathode

Answer 34

positive polarity will increase in size

Question 35

If conjugate redox pair is metal

Answer 35

metal electrode

Question 36

If it does not contain metal

Answer 36

inert electrode (graphite or platnum) for fe4+ and sn 2+

Question 37

If it is a gas

Answer 37

Gas electrode platinum used

Question 38

Two electrolytes

Answer 38

Solution which contains free moving ions

Question 39

Salt bridge

Answer 39

- connects/completes the circuit - provides ions to compensate for those lost/gained during a reation KNO3

Question 40

Voltmeter

Answer 40

records voltage (potential difference) produced by cell

Question 41

External circuit

Answer 41

electrodes+ wire

Question 42

Internal circuit

Answer 42

salt bridge + electrodes