Electrolysis

Question 1

The process:

Answer 1

• when an ionic substance is melted or dissolved, the ions are free to move about within the solution.
• passing a current through substances that are molten means that the solution can be broken down into elements.
• during electrolysis, positively charged ions move to the negative electrode (cathode) and negatively charged ions to the positive electrode (anode).
• ions are discharged at the electrodes, producing elements.

Question 2

What is an electrolyte?

Answer 2

the substance being broken down in electrolysis

Question 3

Where do positively charged ions move?

Answer 3

to the negative electrode (cathode)

Question 4

Where do negatively charged ions move?

Answer 4

the positive electrode (anode)

Question 5

How is electrolysis used to extract metals?

Answer 5

• metals that are more reactive than carbon, so cannot be extracted by carbon, are extracted by electrolysis of molten compounds
• large amounts of energy are used in the extraction process to melt the compounds and to produce the electrical current

Question 6

Electrolysis in aqueous equations:

Answer 6

• the ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved.
• at the negative electrode, hydrogen is produced, unless the metal is less reactive than hydrogen
• at the positive elctrode, a halide ion in produced, but if this isn’t present, oxygen is formed

Question 7

Half equations for positive and negative electrode:

Answer 7

positive electrode: X+ + e- –> X
negative electrode: X- –> e- + X