Electrolysis C6

Question 1

electrolyte

Answer 1

when an ionic compound is melted of dissolved in water, the ions are free to move about within the liquid or solution.
The liquids and solutions can conduct electricity.

Question 2

process of electrolysis

Answer 2

• Passing an electric current through electrolytes causes the ions to move to the electrodes.
• positively charged ions move to the negative electrode(cathode), gain electrons, reduced.
• negatively charged ions move to the positive electrode(anode), lose electrons, oxidized.
• Ions discharged at the electrodes producing elements.

Question 3

What happens when a simple ionic compound is electrolysed in the molten state using inert electodes?

Answer 3

• metal produced at the cathode
• non-metal produced at the anode

Question 4

How are metals extracted from molten compounds?

Answer 4

• metals less reactive than carbon can be extracted by reduction with carbon
• metals more reactive with carbon, electrolysis

Question 5

E.g of metal extraction using aluminium oxide

Answer 5

• aluminium oxide mixed with cryolite, lowers the melting point(reduces amount of energy needed and saves money)
• aluminium ions attracted to the cathode gain 3 electrons to form an aluminium atom.(reduction)
• oxygen ions attracted to anode, loses 2 electrons to form an oxygen atom.

Question 6

disadvantage of electrolysis used to extract metals

Answer 6

anode must be replaced regularly because electrodes made of graphite which is a form of carbon.
- oxygen molecules produced at the anode react with the graphite (carbon dioxide) forming carbon dioxide gas.

expensive
-melting compounds requires large amounts of energy.
- a lot of energy required to produce an electric current

Question 7

what do the ions being discharged in electrolysis of aqueous solutions depend on?

Answer 7

the relative reactivity of the elements involved.

Question 8

what happens at the negative electrode(cathode) in electrolysis of aqueous solutions?

Answer 8

hydrogen is produced if the metal is more reactive than hydrogen

Question 9

what happens at the positive electrode(anode) in electrolysis of aqueous solutions?

Answer 9

Oxygen is produced unless the solution contains halide ions when the halogen is produced.

Question 10

what do water molecules produce when they ionise?

Answer 10

hydroxide and hydrogen ions

Question 11

what does inert mean

Answer 11

unreactive