SC10 Electrolytic Processes Flashcards

1
Q

Define cathode

A

A negative electrode

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2
Q

Define anode

A

A positive electrode

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3
Q

Define electrode

A

A rod of metal or graphite through which an electrical current flows in or out of an electrolyte

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4
Q

Define electrolyte

A

Ionic compound in molten or dissolved solution that conducts the electricity

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5
Q

Define electrolysis

A

The process in which energy, from a direct current supply, decomposes electrolytes

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6
Q

What ions go towards the cathode?

A

Cations

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7
Q

What ions go towards the anode?

A

Anions

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8
Q

What direction do electrons move during electrolysis?

A

From the power supply to the cathode

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9
Q

What occurs at the anode?

A

Negative ions lose their electrons

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10
Q

What occurs at the cathode?

A

Electrons are transferred to the positive ions

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11
Q

What ions will be present in the electrolysis of an aqueous solution?

A
  • The ions of the electrolytes
  • OH- ions
  • H+ ions
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12
Q

Why are OH- and H+ ions present in aqueous solutions?

A

Since aqueous substances are those dissolved in water, water will always be present. Those are the ions present in water

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13
Q

What is produced at the cathode of the electrolysis of an aqueous solution?

A

Hydrogen (from H+ in water) is produced UNLESS the + ions in the ionic compound are from a metal that is less reactive than hydrogen. If the metal is less reactive, it will be produced instead

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14
Q

What are the metals that are less reactive than hydrogen?

A
  • copper
  • silver
  • gold
  • platinum
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15
Q

What is produced at the anode of the electrolysis of an aqueous solution?

A

Oxygen (from the OH-) and water UNLESS there is a group 7 ion present. If so, then it will be produced

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16
Q

What are the ions present in a molten ionic solution?

A

The ions of the solution only

17
Q

What will be produced at the cathode of the electrolysis of a molten solution?

A

The + ions

18
Q

What will be produced at the anode of the electrolysis of a molten solution?

A

The - ions

19
Q

Why must the electrodes used be inert?

A

So they don’t participate with the reaction

20
Q

Define oxidation

A

The loss of electrons

21
Q

Define reduction

A

The gain of electrons

22
Q

Describe the half equation at the cathode

A

X+ - e- = X

23
Q

Where does reduction occur?

A

At the cathode

24
Q

Describe the half equation at the anode

A

X - = X + e-

25
Q

Where does oxidation occur?

A

At the anode

26
Q

What is the anode made of in the formation of copper through the electrolysis of copper sulfate?

A

Impure copper (that we’re purifying)

27
Q

What is the cathode made of in the formation of copper through the electrolysis of copper sulfate?

A

Pure copper

28
Q

What happens in the formation of copper through the electrolysis of copper sulfate?

A
  • Cu2+ ions from the anode move to the cathode, where they gain electrons and are discharged as pure copper
  • impurities form as sludge below the anode
29
Q

What change occurs in the anode during the electrolysis of copper sulfate?

A

It loses mass due to the loss of copper ions and impurities

30
Q

What change occurs in the anode during the electrolysis of copper sulfate?

A

It gains mass as it gains pure copper

31
Q

Is there a change in mass of the solution of copper sulfate during its electrolysis?

A

No, because the loss of mass in the anode is equivalent to the gain of mass of the cathode. Therefore, the concentration of copper ions remains constant

32
Q

Describe what is produced at the cathode and the anode during the electrolysis of copper chloride solution

A

Cathode: Copper
Anode: Chlorine

33
Q

Describe what is produced at the cathode and the anode during the electrolysis of sodium chloride

A

Cathode: H+
Anode: Chlorine

34
Q

Describe what is produced at the cathode and the anode during the electrolysis of sodium sulfate

A

Cathode: H+
Anode: OH-

35
Q

Describe what is produced at the cathode and the anode during the electrolysis of aqueous sulfuric acid

A

Cathode: H+
Anode: OH-

36
Q

Describe what is produced at the cathode and the anode during the electrolysis of molten lead bromide

A

Cathode: Lead
Anode: Bromine