Reactions Flashcards

1
Q

What is displacement

A

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

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2
Q

What affects a displacement reaction

A

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

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3
Q

What is oxidation

A

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

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4
Q

What is reduction

A

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

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5
Q

What is the oxidising agent

A

The chemical that causes oxidation

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6
Q

What is the reducing agent

A

Causes the other chemical to be reduced

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7
Q

What happens with aluminium +iron oxide

A

= 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

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8
Q

What is rusting

A

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

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9
Q

Why does aluminium bot rust

A

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

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10
Q

How canyon prevent rust

A

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

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11
Q

What is electrolysis

A

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

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12
Q

Why does electrolysis only work on ions

A

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

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13
Q

What happens during electrolysis

A

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:

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14
Q

Where are metals and non metals attracted to

A

Metal is formed At the cathode because it is positive

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

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15
Q

What is a cathode

A

Negative electrode

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16
Q

Anode

A

Positive electrode

17
Q

What happens in electrolysis in water

A

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

18
Q

What happens at the cathode

A

Reduction

19
Q

What happens at the anode

A

Oxidation

20
Q

Positive charged particle

A

Anion negative is cation

21
Q

What are the group 1 metals

A

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

22
Q

What happens in each reaction with the group 1 metals

A

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

23
Q

Why are the group 1 metals reactions similar

A

All only have one electron in their outer shell

24
Q

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

A

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

25
Q

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

A

Copper =current x time
——————
50

26
Q

Hydroxide formula for a group 1 metal t

A

NaOH

27
Q

How can copper be purified by electrolysis

A

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

28
Q

How do you extract aluminium from its ore

A

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

29
Q

How is alumina electrolysed

A

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

30
Q

What metals were discovered earlier and why

A

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

31
Q

How is iron made

A
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

32
Q

Why do sodium and aluminium have to be purified by electrolysis

A

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

33
Q

What is the reactivity series

A

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