Chemical Changes (P1)

Question 1

Acid + base → ?

Answer 1

Salt + water

Question 2

How can a neutralisation reaction be written in terms of H+ and OH- ions?

Answer 2

H+ + OH- → H20

Question 3

What is a neutralisation reaction?

Answer 3

An acid and alkali will neutralise each other and produce a salt and water.

Question 4

What is oxidation in terms of oxygen?

Answer 4

Addition of oxygen

Question 5

What is reduction in terms of oxygen?

Answer 5

Removal of oxygen

Question 6

What is oxidation in terms of electrons?

Answer 6

A loss of elections

Question 7

What is reduction in terms of electrons?

Answer 7

A gain of electrons

Question 8

What is a redox reaction?

Answer 8

REDuction and OXidation happens all at the same time so its a redox reaction

Question 9

What is a displacement reaction?

Answer 9

When a more reactive metal will displace a less reactive metal from its compound.

Question 10

How its reactivity determined?

Answer 10

How easily they lose elections - forming positive ions.
The higher up the reactivity series, the more easily it forms positive ions

Question 11

What does the reactivity series tell you about metals reacting with water or acid.

Answer 11

• when a metal reacts with water or acid, they lose electrons and form positive ions.
• so the higher up the reactivity series, the more easily it reacts with water or acid.

Question 12

Acid + metal → ?

Answer 12

Salt + hydrogen

Question 13

Metal + water → ?

Answer 13

Metal hydroxide + hydrogen

Question 14

Which metals react with water?

Answer 14

• More reactive metals will rest with water e.g. potassium, sodium, lithium, and calcium
• less reactive metals will not react with water e.g. Zinc, iron and copper

Question 15

Acid + metal carbonate → ?

Answer 15

Salt + water + carbon dioxide

Question 16

What is the RPA that includes soluble salts and insoluble bases

Answer 16

• You can make soluble salts using insoluble bases

Question 17

What is electrolysis?

Answer 17

The decomposition (breakdown) of a compound using an electric current.

Question 18

Where do the positive ions move towards in electrolysis? + what happens to them?

Answer 18

• Cathode (-ve electrode)
• Gains electrons (reduction)

Question 19

Where do the negative ions move to? And what happens to them?

Answer 19

• Anode (+ve electrode)
• Loss of elections (oxidation)

Question 20

Why is electrolysis expensive?

Answer 20

1. Melting compounds requires a lot of energy
2. A lot energy is required to produce electric current

Question 21

Why can’t ionic solids be electrolysed?

Answer 21

• The ions are in fixed positions + can’t move

Question 22

Why can molten ionic compounds be electrolysed?

Answer 22

• The ions aren’t in a fixed position so can carry a charge

Question 23

What happens as the ions travel to electrodes?

Answer 23

• Creates a flow of charge through the electrolyte

Question 24

Extracting metals: what happens if a metal is less reactive than carbon?

Answer 24

• it can be extracted by carbon

Question 25

Extracting metals: what happens if the metal is more reactive than carbon?

Answer 25

• It can be extracted by electrolysis

Question 26

Why does the anode need to be replaced regularly?

Answer 26

• It is made of graphite not carbon

Question 27

What happens then lead bromide is electrolysed?

Answer 27

• Lead is attracted to the anode (-ve electrode) → gains elections (reduction)
• Bromide is attracted to the cathode (+ve electrode) → loses elections (oxidation)

Question 28

Characteristics of aluminum oxide

Answer 28

• High melting and boiling point
• Can be electrolysed- has free moving ions - can carry a charge

Question 29

What happens to aluminum oxide before electrolysed?

Answer 29

• Aluminum oxide is mixed with cryolite which lowers melting point
  → reduces amount energy and saves money

Question 30

What happens to aluminium oxide during electrolysis?

Answer 30

• Aluminium attracted to cathode - gains 3 elections - reduction
• Oxygen attracted to anode - loses 2 elections - oxidation