Unit 6 - Metals And The Reactivity Series Flashcards Preview

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Flashcards in Unit 6 - Metals And The Reactivity Series Deck (31)
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1
Q

The reactivity series

A

Potassium, sodium, lithium, calcium, magnesium, aluminium, (carbon), zinc, iron, tin, lead, (hydrogen), copper, silver, gold, platinum

2
Q

How are the methods of extraction related to the reactivity of a metal

A

A metal can only be extracted in a blast furnace if the metal is less reactive than carbon. Otherwise, electrolysis is used

3
Q

Main reactions involved in the extraction of iron (blast furnace)

A

Coke is reacted with oxygen to form CO2
C (Coke)+ O2 –> CO2

This Produces heat to decompose the limestone
CaCO3(limestone) –> CaO + CO2

Carbon dioxide is reduced to carbon monoxide by more Coke
CO2 + C –> 2CO

Carbon monoxide is the main reducing agent
3CO + Fe2O3 (haematite) –> 2Fe + 2CO2

Limestone removes impurities such as silica which would make the iron hard and brittle
CaO + SiO2 (silica) –> CaSiO3 (slag)

Molten slag sits on top of the molten iron to stop re-oxidisation. Slag is later used for breeze blocks and motorways. Hot gases emerging from top of blast furnace are mainly nitrogen from the air (with some CO and CO2)

4
Q

Conditions under which iron rusts

A

Iron will react with damp air to form hydrated iron oxide. Water and oxygen are needed

5
Q

How can rusting be prevented

A

Using oil, grease, paint, plastic, or galvanising to stop air and water reaching the surface

6
Q

What is galvanising

A

Dipping the iron into molten zinc so that the iron is completely coated

7
Q

What is sacrificial protection

A

A way of stopping rusting.

By attaching a block of metal more reactive than iron, it will corrode before the iron does. Zinc is often used

8
Q

What are iron alloys known as

A

Steels

9
Q

What is mild steel used for and why

A

Motor car bodies

Malleable

10
Q

What is hard steel used for and why

A

Tools such as chisels, files, and saws

It is hard and strong

11
Q

What is stainless steel used for and why

A

Cutlery, sinks, sculptures

Does not rust

12
Q

Why is titanium steel used for and why

A

Edges of high speed cutting tools, armour plating

Low density, high strength, doesn’t rust

13
Q

Test for Fe++ compounds

A

Dissolve in distilled water
Add sodium hydroxide solution
Fe++ compounds form a moss green gelatinous precipitate : Fe(OH)2

14
Q

Test for Fe +++ compounds

A

Dissolve in distilled water
Add sodium hydroxide solution
Fe+++ compounds form a foxy brown gelatinous precipitate : Fe(OH)3

15
Q

Extraction of aluminium from purified aluminium oxide

A

Aluminium is extracted by electrolysis
First, the aluminium oxide is dissolved in molten cryolite (Na3AlF6) which acts as a solvent as well as reducing the melting point from 2050 degrees to ~950. This reduces the energy needed (cheaper) and increases the conductivity of the Al2O3

Both the electrodes are made of graphite (C) as it conducts electricity and is cheap

The aluminium metal then forms at the cathode
Al+++ add 3e- –> Al (reduction)

The oxygen atoms are then formed at the anode
2O– minus 4e- –> O2 (oxidation)
The positive electrodes have to be replaced often as the oxygen reacts with the carbon to form CO2

16
Q

What happens at the anode and cathode (aluminium extraction)

A

Cathode : reduction
Al+++ (ions) + 3e- –> Al (atoms)

Anode : oxidation
2O– (ion) - 4e- –> O2 (molecules)

17
Q

Test for cation Cu++

A

Add to sodium hydroxide

If test is positive as blue precipitate is formed

18
Q

Describe the laboratory preparation of carbon dioxide

A

Use the thermal decomposition of metal carbonates

Metal carbonate -heat-> metal + carbon dioxide

19
Q

How was the reactivity series made

A

It’s based on the reactions of the metals and their compounds

20
Q

What is the aluminium ore used (before purified aluminium oxide is used)

A

Bauxite

21
Q

What is meant by endothermic

A

Takes in heat, absorbs heat

22
Q

What makes a reaction endothermic

A

Strong forces/bonds between within the compounds need to be broken

23
Q

Equation for cryolite (solvent for aluminium)

A

Na3AlF6

24
Q

Why are the electrodes (electrolysis) made of carbon

A
  • graphite conducts electricity

- high melting point

25
Q

Reduction of hematite by carbon monoxide

A

3CO + Fe2O3 –> 2Fe + 3CO2

26
Q

What element is added to iron to make stainless steel

A

Nickel or chromium

27
Q

Metal + cold water –>

A

Metal hydroxide + hydrogen

28
Q

Potassium and water reaction

A

2K + 2H2O –> 2KOH + 1/2 H2

Metal floats around surface of water, hydrogen is given off, metal sparks and burns with a lilac flame

29
Q

Calcium and cold water reaction

A

Ca + 2 H2O –> Ca(OH)2 + H2
Effervescence of hydrogen
Cloudy white ppt formed
Ca bobs up and down

30
Q

What are the two oxides of copper

A

CuO

Cu2O

31
Q

How to prepare CO2 from copper(II) carbonate

A

Put CuCO3 in a boiling tube with a stopper and tube going down into a beaker. Heat the CuCO3 to produce copper oxide