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1[GCSE Chemistry]1 > Electrolysis > Flashcards

Electrolysis Flashcards

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1
Q

What is electrolysis?

A

The process of using electrical energy to decompose ionic compounds

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2
Q

What is the process of electrolysis?

A

An electric current is passed through an electrolyte (a molten or dissolved ionic compound), causing it to decompose.

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3
Q

What occurs in electrolysis?

A

In electrolysis, oxidation (loss of electrons) and reduction (gain of electrons) occur.

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4
Q

What is the electrolyte?

A

The liquid that is a molten or dissolved ionic compound used in electrolysis

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5
Q

What is the Anode?

A

Positive electrode

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6
Q

What is the cathode?

A

Negative electrode

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7
Q

What is oxidation?

A

The loss of electrons

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8
Q

What is reduction?

A

The gain of electrons

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9
Q

What is the cation?

A

Positive ion that is attracted to the cathode

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10
Q

What is the anion?

A

Negative ion that is attracted to the anode

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11
Q

What is PANIC?

A

Positive Anode Negative Is Cathode

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12
Q

What is OILRIG?

A

Oxidation Is Loss Reduction Is Gain

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13
Q

What do the positive ions (cations) in the electrolyte do?

A

They move towards the cathode (negative electrode) and are reduced (gain electrons) +This creates a flow of charge through the electrolyte

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14
Q

What do the negative ions (anions) in the electrolyte do?

A

They move towards the anode (positive electrode) and are oxidised (lose electrons) +This creates a flow of charge through the electrolyte

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15
Q

What are half equations?

A

They show how electrons are transferred during reactions +They’re useful for showing what happens at each electrode during electrolysis.

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16
Q

What occurs at the cathode?

A

Reduction

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17
Q

What occurs at the anode?

A

Oxidation

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18
Q

What is inert?

A

Unreactive

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19
Q

What happens when the electrolyte is a solution?

A
20
Q

What happens when the electrolyte is a molten ionic substance?

A
21
Q

Why can’t an ionic solid be electrolysed?

A

Because the ions are in fixed positions and can’t move

22
Q

Why can molten ionic compounds be electrolysed?

A

Because their electrons are delocalised so the ions can move freely and conduct electricity

23
Q

In a molten ionic compund, what are positive metal ions reduced to?

A

Metal atoms at the cathode

24
Q

In molten ionic compounds, what are negative ions oxidised to?

A

Atoms or molecules at the anode

25
Q

What are the half equations for the table of molten electrolytes?

A
26
Q

What happens in aqueous solutions?

A

+As well as the ions from the ionic compound, there will be hydrogen ions [H+] and hydroxide ions [OH-]

27
Q

In aqueous solutions, what happens at the cathode?

A

+If H+ ions and metal ions are present, hydrogen gas will be produced if the metal is more reactive than hydrogen [eg. sodium]

+If the metal is less reactive than hydrogen, [eg. copper or silver] then a solid layer of the pure metal will be produced instead.

28
Q

In aqueous solutions, what happens at the anode?

A

If OH- and halide ions [Cl-, Br-, I-] are present, molecules of chlorine, bromine or iodine will be formed.

+If no halide ions are present, then oxygen will be formed

29
Q

What are the half equations of the table of aqueous electrolytes?

A
30
Q

What does the electrolysis of copper sulfate with inert electrodes produce?

A

Oxygen

31
Q

What does a solution of copper sulfate contain?

A
  • Cu2+
  • SO4+2-
  • H+
  • OH-
32
Q

What happens at the cathode when you electrolyse copper sulfate solution with inert electrodes?

A

+Copper is less reactive than hydrogen, so copper metal is produced at the cathode [you see a coating of copper on the electrode]

Cu2++2e- —-> Cu

33
Q

What happens at the anode when you electrolyse copper sulphate solution with inert electrodes?

A

+They’re aren’t any halide ions present, so oxygen and water are produced at the anode [you see bubbles of oxygen gas forming]

4OH-—-> O2 + 2H2O + 4e-

34
Q

What do non-inert electrodes take part in?

A

Electrolysis reactions [eg. copper electrodes]

35
Q

What happens to the anode and cathode when using copper electrodes?

A

As the reaction continues, the mass of the anode will decrease and the mass of the cathode will increase.

+This is because the copper is transferred from the anode to the cathode

36
Q

How long does the non-inert electrolysis reaction take place?

A

+You need to leave the cell running for 30mins in order to get a decent change in mass

37
Q

What is electroplating?

A

Coating the surface of a metal using electrolysis

38
Q

What is the cathode in electroplating?

A

+The object you’re going to electroplate

39
Q

What is the anode in electroplating?

A

The bar of metal you’re using for the plating

40
Q

What is the electrolyte in electroplating?

A

The solution containing the metal ions of the metal you’re plating with

41
Q

Why is electroplating useful?

A

It is used for household objects like cutlery, and cooking utensils are electroplated with metals to stop them from corroding.

+The metals used for electroplating are unreactive and don’t corrode easily.

+Jewellery and decorative items are often electroplated with metals like gold or silver - this improves the appearance of the metals, making them look shiny and attractive.

42
Q

What is the chemical test for chlorine?

A

Damp blue litmus paper test - hold damp blue litmus paper over chlorine.

+Chlorine will bleach the litmus paper, turing it white

43
Q

What is the chemical test for oxygen?

A

+Use a glowing splint

+You can test for oxygen by checking if the gas will relight a glowing splint

44
Q

What is the chemical test for hydrogen?

A

+Use a lighted splint

+Hydrogen makes a “squeaky pop” with a lighted splint.

+The noise comes from the hydrogen burning with the oxygen in the air to form water.

45
Q

What is the test for carbon dioxide?

A

+Bubbling the gas through limewater

+If it is carbon dioxide, the limewater will turn cloudy

1[GCSE Chemistry]1 (35 decks)

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