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h chem w/ sofea! :p > Unit 1: KA3 Oxidising and reducing agents > Flashcards

Unit 1: KA3 Oxidising and reducing agents Flashcards

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1
Q

REDUCTION?

A

Gain of electrons by a reactant in any reaction

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2
Q

OXIDATION?

A

Loss of electrons by a reactant in any reaction

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3
Q

In a redox reaction, when does reduction and oxidation take place?

A

They take place at the same time

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4
Q

What is an OXIDISING agent?

A

A substance that ACCEPTS electrons

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5
Q

What is a REDUCING agent?

A

A substance that DONATES electrons

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6
Q

What can be identified in redox reactions?

A

The OXIDISING and REDUCING agents

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7
Q

Elements with — electronegativities tend to form ions by LOSING electrons (forming ——– ions) and so…

A

LOW.
positive,
act as reducing agents.

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8
Q

Elements with —- electronegativities tend to form ions by GAINING electrons (forming ——– ions) and so…

A

HIGH.
negative,
act as oxidising agents.

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9
Q

Which group in the periodic table will you find the strongest reducing agents?

A

Group 1

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10
Q

Which group in the periodic table will you find the strongest oxidising agents?

A

Group 7

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11
Q

Compounds, group ions and molecules can act as oxidising or reducing agents. These include:
1) Hydrogen peroxide is a molecule that is…
2) Dichromate and permanganate ions are group ions that are strong…
3) Carbon monoxide is a gas that can be used as a…

A

1) Hydrogen peroxide = an OXIDISING agent
2) Dichromate and permanganate ions = strong OXIDISING agents in acidic solutions.
3) Carbon monoxide = a REDUCING agent

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12
Q

Oxidising agents are widely used because…

A

They can KILL FUNGI AND BACTERIA EFFECTIVELY,
&
They can INACTIVATE VIRUSES.

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13
Q

The oxidation process is also an effective means of…

A

Breaking down coloured compounds –> making oxidising agents ideal for use as ‘bleach’ for clothes and hair.

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14
Q

What does the ELECTROCHEMICAL SERIES represent?

A

It represents a series of reduction reactions.

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15
Q

Where are the STRONGEST OXIDISING AGENTS (with regards to the electrochemical series)?

A

At the bottom of the left-hand column of the electrochemical series.

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16
Q

Where are the STRONGEST REDUCING AGENTS (with regards to the electrochemical series)?

A

At the top of the right-hand column of the electrochemical series.

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17
Q

How can an ion-electron equation be balanced?

A

By adding appropriate numbers of WATER molecules, HYDROGEN IONS and ELECTRONS.

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18
Q

Ion-electron equations can be combined to produce…

A

REDOX EQUATIONS.

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19
Q

An oxidising agent ——– something else.
The oxidising agent itself is ——- and ——- electrons.
OXIDISING AGENTS TENDS TO BECOME MORE ——–.

A

OXIDISES,
REDUCED,
accepts/gains,
NEGATIVE.

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20
Q

A reducing agent ——- something else.
The reducing agent itself is ——– and —– electrons.
REDUCING AGENTS TEND TO BECOME MORE ——–.

A

REDUCES,
OXIDISED,
loses,
POSITIVE.

21
Q

What is acidified permanganate solution an example of?
MnO₄⁻+ 8H⁺ + 5e⁻ –> Mn²⁺ + 4H₂O

A

An oxidising agent which gains electrons.

22
Q

What are sulphite ions an example of?
SO₃²⁻ + H₂O –> SO₄²⁻ + 2H⁺ + 2e⁻

A

A reducing agent which loses electrons.

23
Q

Electronegativity can be used to…

A

predict which elements lose or gain electrons when they form ions.

24
Q

Does Potassium accept/lose electrons?

A

They lose electrons because they have a low electronegativity value (0.8)
K –> K⁺ + e⁻

25
Q

Does Lithium accept/lose electrons?

A

They lose electrons because they have a low electronegativity value (1.0).
Li –> Li⁺ + e⁻

26
Q

Does Chlorine accept/lose electrons?

A

They accept electrons because they have a high electronegativity value (3.0).
Cl + e⁻ –> Cl⁻

27
Q

Does Fluorine accept/lose electrons?

A

They accept electrons because they have a high electronegativity value (4.0).
F + e⁻ –> F⁻

28
Q

Group 1 elements are the weakest reducing agents. True or False?
Where are the strongest REDUCING agents located in the Electrochemical Series?

A

False, Group 1 elements are the STRONGEST reducing agents.
They’re found at the top of the right-hand column of the electrochemical series.

29
Q

Group 7 elements are the strongest oxidising agents. True or False?
Where are the strongest OXIDISING agents located in the Electrochemical Series?

A

True.
At the bottom left of the electrochemical series.

30
Q

Acidified peroxide is an oxidising agent as it…

A

accepts electrons and is reduced itself.

31
Q

Acidified dichromate is an oxidising agent as it…

A

accepts electrons and is reduced itself.

32
Q

Carbon monoxide is a reducing agent as it…

A

loses electrons and is oxidised itself.

33
Q

If the reduction reaction in electrochemical series is reversed, it becomes an…

A

Oxidation reaction

34
Q

When given the reactant and product species, how do you write ion-electron equations?

A

1) Write down the main species involved in the reaction: IO₃⁻ –> I₂
2) Balance all atoms except O and H: 2IO₃⁻ –> I₂
3) Add H₂O to other side to balance O atoms: 2IO₃⁻ –> I₂ + 6H₂O
4) Add H⁺ ions to other side to balance H atoms: 2IO₃ + 12H⁺ –> I₂ + 6H₂O
5) Add e⁻ to most positive side to balance charge: 2IO₃ + 12H⁺ + 10e⁻ –> I₂ + 6H₂O

35
Q

Can ion-electron equations be combined to produce redox equations?

A

Yes

36
Q

Combine the reduction equation for Iodine and the oxidation equation for S₄O₆ for your REDOX reaction equation!

A

REDUCTION EQUATION:
I₂ + 2e⁻ –> 2I⁻
OXIDATION EQUATION (flip equation):
2S₂O₃²⁻ –> S₄O₆²⁻ + 2e⁻
(balance out electrons)
REDOX REACTION:
I₂ + 2S₂O₃²⁻ –> S₄O₆²⁻ + 2I⁻
(get rid of the electrons)

37
Q

Where the electrons don’t cancel out, ion-electron equations may have to be multiplied. How do you do this?

A

EXAMPLE:
1) MnO₄⁻ + 8H⁺ + 5e⁻ –> Mn²⁺ + 4H₂O
Fe²⁺ –> Fe³⁺ + e⁻
2) Balance the electrons by multiplying:
MnO₄⁻ + 8H⁺ + 5e⁻ –> Mn²⁺ + 4H₂O
5Fe²⁺ –> 5Fe³⁺ + 5e⁻
3) Cancel the electrons out. —> 5e⁻
4) MnO₄⁻ + 8H⁺ + 5Fe²⁺ –> Mn²⁺ + 4H₂O + 5Fe³⁺

38
Q

Oxidising agents will be ——-.
Reducing agents will be ——–.

A

Reduced.
Oxidised.

39
Q

Fluorine with an electronegativity value of 4.0 will be a strong reducing agent. True or False?

A

False, Fluorine will be a strong OXIDISING agent, and so will itself be reduced (due to its strong attraction for electrons).

40
Q

Some metals are more reactive than others (refer to the reactivity series).
In an experiment, a strip of metal is added to a solution of another.
If the metal is MORE REACTIVE than the metal in solution, this metal…

A

displaces (pushes out) the less reactive solution.

41
Q

A metal higher in the series?
Metal atoms will be ——–.
They are the ——– agent.

Zn and Cu Redox Experiment. Write the oxidation equation for the reducing agent.

A

OXIDISED.
REDUCING
eg. Zn –> Zn²⁺ + 2e⁻

42
Q

A metal lower in the series?
Metal ions will be ——-.
Metal ions are the ——— agent.

Zn and Cu Redox Experiment.
Write the reduction equation for the oxidising agent.

A

REDUCED.
OXIDISING
eg. Cu²⁺ + 2e⁻ –> Cu

43
Q

Potassium permangate is used in…

A

fish ponds to treat common fish pathogens such as gill parasites and external bacterial and fungal infections.

44
Q

You can use diluted potassium permanganate to…

A

treat athlete’s foot (a fungal infection) in humans.

45
Q

Hydrogen peroxide oxidises…

A

coloured pigments in hair (related to melanin) to colourless substances

46
Q

How does Chlorine in swimming pools work?

A

Chlorine breaks down into many different chemicals, including hypochlorous acid (HOCL). The hypochlorous acid is a strong oxidising agent and kills microorganisms by removing electrons from the bacteria –> destroying the cell walls and enzymes and structures inside the cell, rendering them harmless.

47
Q

Sodium hypochlorite acts as a…

A
  • powerful disinfectant.
    In solution, the hypochlorite ions from hypochlorous acid, HClO. This is the oxidising agent.
    Household bleach is, in general, a solution containing 4-6% sodium hypochlorite.
48
Q

CO (carbon monoxide) is a

A

strong reducing agent and reduces metal oxides to form metals.

h chem w/ sofea! :p (3 decks)

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