Chemical Changes

Question 1

Acids ionise in water to produce….

Answer 1

hydrogen ions H+

Question 2

Alkalis ionise in water to produce….

Answer 2

Hydroxide ions, OH-

Question 3

What is a base?

Answer 3

A substance that neutralises an acid

Question 4

Suggest the pH of hydrochloric acid

Answer 4

1-4

Question 5

Suggest the pH of sodium hydroxide

Answer 5

10-14

Question 6

Acid + Metal =

Answer 6

Salt + Hydrogen (MASH)

Question 7

Acid + Metal Oxide =

Answer 7

Salt + Water

Question 8

Acid + Alkali =

Answer 8

Salt + Water

Question 9

Acid + Metal Carbonate =

Answer 9

Salt + carbon dioxide + water

Question 10

Magnesium + Hydrochloric acid =

Answer 10

Magnesium Chloride + Hydrogen

Question 11

Sodium Hydroxide + Nitric acid =

Answer 11

Sodium nitrate + water

Question 12

Copper Oxide + sulphuric acid =

Answer 12

Copper sulphate + water

Question 13

Calcium Carbonate + Hydrochloric acid =

Answer 13

Calcium chloride + Carbon Dioxide + water

Question 14

List the steps to make copper sulphate crystals

Answer 14

Warm sulphuric acid Add copper oxide until it is in excess Filter the excess copper oxide Evaporate the water in an evaporating dish

Question 15

How can a precipitate, such as lead iodide, be removed from a solution?

Answer 15

Filter it

Question 16

What is the positive electrode in electrolysis called?

Answer 16

Anode (PANic)

Question 17

What is the negative electrode in electrolysis called?

Answer 17

Cathode (PANiC)

Question 18

In the electrolysis of lead iodide, why does the lead iodide have to be melted?

Answer 18

so the ions can move and carry the charge

Question 19

In the electrolysis of lead iodide, which electrode do the lead ions go to?

Answer 19

Cathode

Question 20

Explain why copper ions go to the cathode

Answer 20

The cathode is negative Copper ions are positive Opposite charges attract

Question 21

Explain why chloride ions go to the anode

Answer 21

The anode is positive Chloride ions are negative Opposite charges attract

Question 22

Finish the following equation Pb²⁺ + __ e^- –> Pb

Answer 22

Pb²⁺ + 2e^- –> Pb

Question 23

How does a copper ion, Cu²⁺, become a copper ion?

Answer 23

By gaining two electrons

Question 24

What is the aluminium ore called?

Answer 24

Bauxite

Question 25

Why is molten cryolite added to the aluminium oxide?

Answer 25

To reduce the melting point so less energy is required

Question 26

Name the three products of the electrolysis of brine

Answer 26

Sodium hydroxide Hydrogen Chlorine (CatHy’s AnCls)

Question 27

The loss of electrons is called

Answer 27

Oxidation (OILRIG)

Question 28

The gain of electrons is called

Answer 28

Reduction (OILRIG)

Question 29

Why is hydrogen produced instead of sodium in the electrolysis of brine?

Answer 29

Sodium is more reactive than hydrogen

Question 30

Why can carbon be used to extract copper from copper oxide?

Answer 30

Carbon is more reactive

Question 31

Why can’t aluminium be extracted from aluminium oxide by reducing it with carbon?

Answer 31

Aluminium is more reactive

Question 32

In electrolysis of aluminium, why do the electrodes need to be replaced?

Answer 32

-The electrodes are made of carbon -They react with the oxygen -To form carbon dioxide