electrolysis

Question 1

what is electrolysis

Answer 1

the breakdown of an ionic compound by the passage of electricity

Question 2

what is the vessel electrolysis takes place in called

Answer 2

electrolysis cell

Question 3

what is the electrode

Answer 3

a rod of metal or graphite which leads an electric current to or from an electrolyte

Question 4

what is an electrolyte

Answer 4

an ionic compound which conducts electricity when molten or dissolved in water

Question 5

what is an anode

Answer 5

the positive electrode

Question 6

what is a cathode

Answer 6

the negative electrode

Question 7

what is an anion

Answer 7

a negative ion

Question 8

what is a cation

Answer 8

a positive ion

Question 9

what ion moves to what electrode

Answer 9

cations move to the cathode and anions move to the anode during electrolysis

Question 10

what happens when inert graphite of platinum electrode are used

Answer 10

metal or hydrogen is formed at the negative electrode (cathode). This is because the ions moving towards the negative electrodes are positively charged.

non-metals other than hydrogen are formed at the positive electrode (anode). This is because the ions moving towards the positive electrode as negatively charged.

Question 11

electrolysis of molten lead (II) bromide

Answer 11

cathode - lead

anode - bromine

Question 12

electrolysis of aqueous copper chloride

Answer 12

cathode - copper

anode- chlorine

Question 13

electrolysis of dilute sulphuric acid

Answer 13

cathode - hydrogen

anode - oxygen

Question 14

the making of aluminium

Answer 14

aluminium has a very high melting point of 2054 degrees celsius. cryolite is used to reduce the melting point to 700 degrees celsius to make aluminium easier to extract. for electrolysis, the ore is dissolved in a compound. At the anode is oxygen and the cathode is aluminium

Question 15

purification of copper

Answer 15

used for wiring and making components

the extraction of copper from copper ore is done by reduction with carbon

Question 16

electrolysis of copper

Answer 16

the positive electrode (the anode) is made of impure copper which is to be purified. The negative electrode (cathode) is a bar of pure copper. The two electrodes are placed in a solution of copper sulphate. copper ions leave the anode and are attracted to the cathode, where they are deposited as copper atoms. The pure copper cathode increases in size and the anode dwindles away. The impurites left behind from the anode forms a sludge beneath it.

Question 17

what is brine made from

Answer 17

water and sodium chloride

Question 18

what is the electrolysis of brine used for

Answer 18

to extract chlorine from salt. sodium hydroxide and hydrogen is also obtained from this.

Question 19

what cannot mix in the electrolysis of brine

Answer 19

chlorine and sodium hydroxide produced in the process have to be separated as they react with each other

Question 20

uses of chlorine

Answer 20

purification of water

making plastics

Question 21

sodium hydroxide

Answer 21

making detergents

making paper

Question 22

hydrogen

Answer 22

making margarine

make fertilisers