revision topic 5

Question 1

what is the meaning of Electrolysis

Answer 1

it’s the breaking down using electricity, where an electric current is used to break down an ionic substance called an electrolytes

Question 2

what is the positive electrode?

Answer 2

anode

Question 3

what is the negative electrode

Answer 3

cathode

Question 4

what happens during electrolysis in terms of ions

Answer 4

positively charged ions go to the cathode and negatively charged ions go to the anode

Question 5

in electrolysis, the ions in the anode are always?

Answer 5

oxidized to become balanced i.e neutral

Question 6

in electrolysis, the ions in the cathode are always?

Answer 6

reduced to become balanced i.e neutral

Question 7

in a solution what is the rule for the element forming at the cathode

Answer 7

hydrogen is always formed in the cathode unless there is a less reactive positive ion there

Question 8

in a solution what is the rule for the element forming at the anode

Answer 8

oxygen is always formed in the anode unless there is a halogen present

Question 9

what is the half equation for hydroxide ions

Answer 9

4OH- ——-> 2H2O + O2 + 4e-

Question 10

from what ore is Aluminium extracted from

Answer 10

bauxite

Question 11

what’s the problem with electrolyzing Aluminum ore and how do we solve it

Answer 11

it has a high melting point so it requires a lot of energy to break to avoid that we would use motel cryolite as a catalyst to lower the melting point

Question 12

in aluminum electrolysis what is formed in the cathode and its half equation

Answer 12

Aluminum is formed and its half equation is:

Al3+ ———-> Al - 3e-

Question 13

in aluminum electrolysis what is formed in the anode and its half equation

Answer 13

oxygen is formed and its half equation is:

2O2- ——> O2 + 4e-

Question 14

what are the 3 useful products formed in the electrolysis of brine

Answer 14

chlorine gas, hydrogen gas, and sodium hydroxide solution

Question 15

in the electrolysis of brine what is formed in the cathode and the half equation

Answer 15

hydrogen gas and it’s half equation is:

H2+ ——> 2H - 2e-

Question 16

in the electrolysis of brine what is formed in the anode and the half equations

Answer 16

chlorine solution and it’s half equation is:

Cl2- ——> 2CL + 2e-

Question 17

how can you extract a sodium hydroxide from brine electrolysis?

Answer 17

at the cathode when hydrogen gets extracted from the hydrogen it leaves hydroxide ions which react with sodium to form sodium hydroxide, in order to prevent the mixture of sodium chloride and sodium hydroxide a porous membrane is used to separate the cathode and the anode extracting the pure sodium hydroxide

Question 18

how can we use chlorine

Answer 18

by making bleach which is made by reacting

Question 19

how can we use hydrogen

Answer 19

by making margarine which is made by reacting hydrogens with vegetable oil

Question 20

how can we use sodium hydroxide

Answer 20

by making soup, paper, and bleach

Question 21

what is an electroplated object

Answer 21

It an objected coated by a thin layer of metal by electrolysis

Question 22

why would we electroplate an object

Answer 22

1. to protect the metal beneath from corroding
2. to make an object look more attractive
3. to in the hardness of the surface and its resistance to scratching
4. to save money by making cheaper jewelry

Question 23

how does electroplating work

Answer 23

the metal object to be plated is used as the cathode and the plating metal is put in the anode, so the ions from the plating metal would go to the negative cathode plating the mental that’s was placed there

Question 24

what is the half equation that happens in the anode in an electroplating

Answer 24

product then reactants

Question 25

what is the half equation that happens in the cathode in the electroplating

Answer 25

reactants then products

Question 26

what are inert electrodes

Answer 26

they are electrodes that dont take place in electrolysis for example carbon metal electrodes

Question 27

what are active electrodes

Answer 27

they are electrodes that take place in electrolysis for example metal electrodes

Question 28

when using active electrodes what happens to the electrodes

Answer 28

the anode would lose mass since the ions in it are positive so they would go to the cathode making the cathode gain mass hence:

the loss in mass of active electrode at the anode = the gain in mass of active electrode at the cathode