Electrochemistry 🧪

Question 1

When an electric current is passed through a molten ionic compound or aqueous solution of ionic compounds

Answer 1

The compound decomposes or breaks down

Question 2

Covalent compounds can’t conduct electricity because

Answer 2

They do not undergo electrolysis

Question 3

Ionic compounds in the solid state cannot conduct electricity either since

Answer 3

They have no free ions that can move and carry the charge

Question 4

Electrode

Answer 4

A rod of metal or graphite which an electric current flows into or out of an electrolyte

Question 5

Electrolyte

Answer 5

Is the ionic compound in a molten or dissolved solution that conducts the electricity

Question 6

Anode

Answer 6

The positive electrode of an electrolysis cell

Question 7

Anion

Answer 7

A negatively charged ion which is attracted to the anode

Question 8

Cathode

Answer 8

The negative electrode of an electrolysis cell

Question 9

Cation

Answer 9

A positively charged ion which is attracted to the cathode

Question 10

Metals and hydrogen form positively charged ions so

Answer 10

Either a metal or hydrogen gas is formed at the cathode

Question 11

Non-metals form negatively charged ions and so

Answer 11

non-metals (except hydrogen) are formed at the anode

Question 12

PANIC

Answer 12

Positive Anode Negative Is Cathode

Question 13

During electrolysis,

Answer 13

current needs to flow around the circuit

Question 14

In order for current to flow around the circuit

Answer 14

Charge must be transferred around the circuit by charge carriers

Question 15

The power supply provides the cathode with

Answer 15

A supply of electrons, causing it to become negatively charged

Question 16

Positive ions (Cathodes) in the electrolyte move

Answer 16

Towards the cathode where they gain electrons

Question 17

Negative ions (anions) move towards

Answer 17

The anode where they lose electrons

Question 18

The electrons move from the

Answer 18

Anode back towards the power supply

Question 19

Electrons are

Answer 19

The charge carriers in the external circuit

Question 20

Ions are

Answer 20

The charge carriers in the electrolyte

Question 21

A binary ionic compound

Answer 21

Is one consisting of just 2 elements joined together by ionic bonding. When these compounds undergo electrolysis they always produce their corresponding elements

Question 22

The cathode product

Answer 22

Will always be the metal

Question 23

The product formed at the anode

Answer 23

Will always be the non-metal

Question 24

Brine can be electrolysed, when it is it

Answer 24

Produces bubbles of gas at both electrodes as chlorine and hydrogen are produced leaving behind sodium hydroxide solution

Question 25

Dilute sulfuric acid can be electrolysed, when it is

Answer 25

Bubbles of gas are seen at both electrodes. At the negative electrode H+ ions are attracted to the cathode and form hydrogen gas. OH- ions are attracted to the anode and form Oxygen gas and Water

Question 26

Determining what gas is produced Oxygen Chlorine Hydrogen

Answer 26

Oxygen: glowing splint relights Chlorine: blue litmus paper turns red then white Hydrogen: squeaky pop sound

Question 27

Aqueous solutions will always have

Answer 27

Water present

Question 28

In the electrolysis of aqueous solutions

Answer 28

Water molecules dissociate producing H+ and OH- ions these ions are also involved in the process and their chemistry must be considered

Question 29

Now there is an electrolyte containing

Answer 29

ions from the compound plus ions from the water

Question 30

Which ions gat discharged and at which electrode depends on

Answer 30

The relative reactivity of the. Ions involved

Question 31

Concentrated and dilute solutions of the same compound give

Answer 31

Different products, for anions the more concentrated ion will tend to be discharged over a more dilute ion

Question 32

Negatively charged OH- ions and non metal ions are attracted to

Answer 32

The positive electrode

Question 33

If halide ions (Cl-, Br-,I-) and OH- are present then

Answer 33

The halide ion is discharged at the anode, loses electrons and forms a halogen

Question 34

If no halide ions are present

Answer 34

Then OH- is discharged at the anode, loses electrons and forms Oxygen gas

Question 35

The concentration of the solution also affects which ion is discharges

Answer 35

Concentrated halide solution: the halogen forms at the anode Dilute halide solution: oxygen is formed at the anode

Question 36

Positively charged H+ and metals ions are attracted

Answer 36

to the negative electrode but only one will gain electrons. Either hydrogen gas or metal will be produced

Question 37

If the metal is above hydrogen in the reactivity series

Answer 37

Then hydrogen will be produced and bubbling will be seen at the cathode this is because the ions of the more reactive metal will remain in the solution causing the ions of the least reactive metal to be discharged

Question 38

At the cathode hydrogen will be produced unless,

Answer 38

The positive ions from the ionic compound are less reactive than hydrogen, in which case the metal is produced

Question 39

Reactivity series

Answer 39

Potassium Sodium Lithium Calcium Magnesium Aluminum Carbon Zinc Iron Hydrogen Copper Silver Gold