Topic 4 - Flashcards

1
Q

An electrolysis cell has two electrodes. What is the name of the positive electrode?

A

Anode

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2
Q

What is the liquid called in an electrolysis reactions?

A

Electrolyte

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3
Q

In electrolysis, which direction do the electrons travel?

A

Anode ➔ Cathode

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4
Q

Which ions are attracted to the negative electrode (cathode) during electrolysis?

A

Positive ions (opposite charges attract)

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5
Q

The electrodes in an electrolysis cell are normally made of inert carbon. What does the term ‘inert’ mean?

A

It is unreactive, so will not take place in the reaction.

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6
Q

In electrolysis, is the ion that gains electrons oxidised or reduced?

A

Reduced

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7
Q

In the electrolysis of molten lead bromide, what is the product at the anode?

A

Bromine

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8
Q

In terms of electrons, what does oxidation mean?

A

Loss of electrons

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9
Q

In electrolysis, why does the compound you’re trying to separate need to be molten or dissolved?

A

So that the ions are free to move around (and go to their respective electrode)

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10
Q

In electrolysis, which electrode would chloride ions (Cl-) be attracted to?

A

Anode

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11
Q

Which two of the following chemical processes are used to extract metals from their ores?

A

Electrolysis

Reduction with carbon

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12
Q

How is a metal extracted from a metal compound using electrolysis?

A

A compound is split into its elements using electricity

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13
Q

Why is electrolysis not used to extract all metals?

A

Electrolysis is expensive because it requires a large amount of electricity

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14
Q

When should a metal be extracted by carbon reduction?

A

When the metal is less reactive than carbon

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15
Q

Why is electrolysis used to extract aluminium from its ores?

A

It is more reactive than carbon

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16
Q

What is the name of the substance that is mixed with aluminium oxide to lower its melting point?

A

Cryolite

17
Q

In the electrolysis of a solution, which two ions are present from the water molecules themselves?

A

H+
OH-

18
Q

In the electrolysis of aqueous solutions, what is the rule for determining which ion will be oxidised (lose electrons) at the anode (positive electrode)?

A

It will always be the OH-, unless there is a halide ion (such as Cl-, or Br-) present

19
Q

In the electrolysis of aqueous solutions, what is the rule for determining which ion will be reduced (gain electrons) at the cathode (negative electrode)?

A

It will always be the H+ ion, unless Cu2+ is present (another way of phrasing it would be that it is always the ion of the least reactive element)