Reactions

Question 1

What is displacement

Answer 1

A more reactive metal will displace a less reactive metal from a compound

Question 2

What affects a displacement reaction

Answer 2

The greater difference in reactivity between the two metals the greater the amount of energy released

Question 3

What is oxidation

Answer 3

The loss of electrons from a substance . It is also the gain of oxygen by a substance e.g 2mg +O2 = 2mgo oil

Question 4

What is reduction

Answer 4

The gain of electrons by a substance it is also the loss of oxygen from a substance e.g copper oxide can be reduced to form copper when it reacts with hydrogen. Copper oxide +hydrogen - copper and water rig

Question 5

What is the oxidising agent

Answer 5

The chemical that causes oxidation

Question 6

What is the reducing agent

Answer 6

Causes the other chemical to be reduced

Question 7

What happens with aluminium +iron oxide

Answer 7

= iron + aluminium oxide
The aluminium has been oxidised this means iron oxide is the oxidising agent and iron oxide has been reduced so aluminium is the reducing agent

Question 8

What is rusting

Answer 8

An oxidation reaction. The iron reacts with water and oxygen to form hydrated iron oxide(rust) . Iron +water +oxygen = hydrated iron oxide

Question 9

Why does aluminium bot rust

Answer 9

Because it’s surface is protected by a natural layer of aluminium oxide

Question 10

How canyon prevent rust

Answer 10

Stop oxygen or water reaching the metals surface . Like galvanising - the iron or steep object is coated in a thin layer of zinc that stops oxygen or water reaching the metal underneath , it also acts as a sacrificial metal as it is more reactive than iron so it oxidises in preference to the iron object

Question 11

What is electrolysis

Answer 11

Electrolysis is the process by which ionic substances are decomposed into simpler substances when an electric current is passed through them

Question 12

Why does electrolysis only work on ions

Answer 12

Electricity is the flow of electrons , for electrolysis to work the compound must contain ions , covalent compounds don’t work as they contain neutral atoms instead of ions. The ions must also be free to move which is possible when they are dissolved in water or melted

Question 13

What happens during electrolysis

Answer 13

Positively charged ions move to the cathode they receive electrons and are reduced
Negatively charged ions move to the anode electrode , they lose electrons and are oxidised:

Question 14

Where are metals and non metals attracted to

Answer 14

Metal is formed At the cathode because it is positive

Non metal element is formed at the anode because it is negative

Question 15

What is a cathode

Answer 15

Negative electrode

Question 16

Anode

Answer 16

Positive electrode

Question 17

What happens in electrolysis in water

Answer 17

If the metal is less reactor than hydrogen metal will be produced t the cathode .if it is more reactive than hydrogen than hydrogen will be produced at the cathode

Question 18

What happens at the cathode

Answer 18

Reduction

Question 19

What happens at the anode

Answer 19

Oxidation

Question 20

Positive charged particle

Answer 20

Anion negative is cation

Question 21

What are the group 1 metals

Answer 21

They from alkaline solutions when they react with water , this is why they are called the alkali metals

Question 22

What happens in each reaction with the group 1 metals

Answer 22

Hydrogen gas is given off and the ( metal) hydroxide is produced , the speed and violence of these reactions increased as you go down the group

Question 23

Why are the group 1 metals reactions similar

Answer 23

All only have one electron in their outer shell

Question 24

Why does the reactivity do the group 1 metals increase as you go down the group

Answer 24

The atoms get larger as you go down the group
The outer electron gets further from the nucleus as you go down the group
The attraction between the nucleus and outer electron gets weaker as you go down the group

Question 25

What is the link between the current and time copper is electrolysed for

Answer 25

Copper =current x time ------------------ 50

Question 26

Hydroxide formula for a group 1 metal t

Answer 26

NaOH

Question 27

How can copper be purified by electrolysis

Answer 27

If you electrolyse copper sulphate solution using copper electrodes , the anode dissolves into the solution and pure copper is coated onto the cathode

Question 28

How do you extract aluminium from its ore

Answer 28

Bauxite - purified - alumina (al2o3) - electrolysis - aluminium

Question 29

How is alumina electrolysed

Answer 29

Molten cryolite is used to dissolve the alumina and layer of carbon acts as the cathode so At the anode - 60(2-) - 12e = 3o2 At the cathode 4al (3+) + 12 e = 4al

Question 30

What metals were discovered earlier and why

Answer 30

The lower metals are on the reactivity series , the earlier they were discovered as they were easy to reduce with carbon or were able to be thermally decomposed like lead and copper to then be reduced with carbon : . E.g copper carbonate + heat= CuO + Co2 Metals above carbon in the reactivity series had to be purified using electrolysis which was discovered much later

Question 31

How is iron made

Answer 31

``` Iron ore (iron oxide) is put in a blast furnace with alternate layers of coke - coke = carbon burns in air to produce heat, and reacts to form carbon monoxide (needed to reduce the iron oxide) limestone =calcium carbonate -helps to remove acidic impurities from the iron by reacting with them to form molten slag ``` air - oxygen allows the coke to burn, and so produces heat and carbon monoxide In the blast furnace, it is so hot that carbon monoxide can be used to reduce the iron oxide in place of carbon: iron oxide + carbon monoxide → iron + carbon dioxide Fe2O3 + 3CO → 2Fe + 3CO2 Molten iron then sinks to the bottom of the blast furnace as it is densest and the less dense slags comes out the slag notch

Question 32

Why do sodium and aluminium have to be purified by electrolysis

Answer 32

Because they are higher than carbon so can't be displaced by it

Question 33

What is the reactivity series

Answer 33

Potassium , sodium , lithium , calcium , magnesium , aluminium , carbon , zinc , iron , hydrogen , copper , silver , gold