Eletrolysis

Question 1

What is electrolysis?

Answer 1

The decomposition of a compound using electricity.

Question 2

What is the electrolyte in electrolysis?

Answer 2

The compound (molten or aqueous) that is being decomposed by the electricity.

Question 3

What is the positive electrode called in electrolysis?

Answer 3

Anode.

Question 4

What type of ions are attracted to the anode?

Answer 4

Anions / negative ions.

Question 5

What occurs at the positive electrode during electrolysis?

Answer 5

Negatively charged ions lose electrons - oxidation.

Question 6

What is the negative electrode called in electrolysis?

Answer 6

Cathode.

Question 7

What type of ions are attracted to the cathode?

Answer 7

Cations / positive ions.

Question 8

What occurs at the negative electrode during electrolysis?

Answer 8

Positively charged ions gain electrons - reduction.

Question 9

What happens to solid ionic compounds during electrolysis?

Answer 9

The ions are in a fixed lattice and are not free to move.

Question 10

What is the state of ionic compounds that allows them to conduct electricity?

Answer 10

Molten or aqueous.

Question 11

What do molten ionic liquids split into during electrolysis?

Answer 11

Their elements.

Question 12

What is produced at the cathode during electrolysis?

Answer 12

Metals.

Question 13

What is produced at the anode during electrolysis?

Answer 13

Non-metals.

Question 14

What makes the electrolysis of aqueous ionic compounds more complicated?

Answer 14

The presence of more ions, including H+ and OH- ions.

Question 15

At the cathode, what determines whether a metal ion or hydrogen forms?

Answer 15

The reactivity of the metal compared to hydrogen.

Question 16

If the metal is less reactive than hydrogen, what will form at the cathode?

Answer 16

The metal.

Question 17

At the anode, what competes for discharge against non-metals?

Answer 17

OH- ions.

Question 18

If the non-metal is a halide (F, Cl, Br, I), what will always be discharged at the anode?

Answer 18

The halogen.

Question 19

What is an example of a halogen forming during electrolysis?

Answer 19

Chloride becoming chlorine (Cl2).

Question 20

What occurs if the non-metal is not a halide during electrolysis?

Answer 20

OH- will discharge into O2 + H2O.

Question 21

What is one way to set up an electrolysis experiment to obtain gas?

Answer 21

Using inverted test tubes or a gas syringe.

Question 22

What is the test for chlorine gas?

Answer 22

It bleaches damp litmus paper, turning it white.

Question 23

What sound does hydrogen make when burned with a lighted splint?

Answer 23

A squeaky pop.

Question 24

What happens to a glowing splint in the presence of oxygen?

Answer 24

It relights.

Question 25

What is the primary ore of aluminium?

Answer 25

Bauxite (Al2O3).

Question 26

How are metals extracted from their ores using electrolysis?

Answer 26

By melting the ore and producing the required current.

Question 27

Why is electrolysis used for extracting certain metals?

Answer 27

When the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon.

Question 28

What is the role of cryolite in the extraction of aluminium?

Answer 28

It lowers the operating temperature by allowing the mixture to move freely at a lower temperature.

Question 29

What do the positive Al³⁺ ions do during electrolysis?

Answer 29

They are attracted to the negative electrode, pick up three electrons each, and turn into neutral aluminium.

Question 30

What do the negative O²⁻ ions do during electrolysis?

Answer 30

They are attracted to the positive electrode, lose two electrons, and form neutral oxygen atoms.

Question 31

What is a consequence of using carbon electrodes in electrolysis?

Answer 31

The anodes need to be replaced often as they react with oxygen to form carbon dioxide.

Question 32

What do half equations show?

Answer 32

The reactions that happen at the electrodes.

Question 33

Fill in the blank: For the electrolysis of aqueous sodium chloride, the half equation for hydrogen is _______.

Answer 33

2H⁺ + 2e⁻ → H₂

Question 34

What is the ionic equation for the electrolysis of aqueous sodium chloride?

Answer 34

2H⁺ + 2Cl⁻ → H₂ + Cl₂

Question 35

What is a method to obtain copper from copper sulfate?

Answer 35

By displacement with scrap iron or by electrolysis.

Question 36

What are the two processes mentioned for obtaining copper from ores?

Answer 36

• Bioleaching
• Phytomining