C10. Metals Flashcards
List the physical properties of metals.
- Generally solids at room temperature
- Ductile
- Malleable (can be beaten into a different shape with a hammer)
- Conductor of electricity and heat
- High densities
- High boiling and melting points
- Hard
- Shiny
- Strong
- Sonorous
List the physical properties of most non-metals.
- Low densities
- Does not conduct heat
- Does not conduct electricity
- Not malleable
- Dull surface
- Not ductile
- Not sonorous
List the chemical properties of metals.
- Many metals react to give off hydrogen gas
- When they react, metals form positive ions by losing electrons
- Many metals are basic.
List the chemical properties of non-metals.
- Non-metal are acidic.
- Most do not react with acids
- When they react with metals, non-metals form negative ions by gaining electrons.
What is an ‘alloy’?
A mixture of two or more metals, or one or more metal with a non-metal.
What are uses of alloys?
Improve strength, hardness or resistance to corrosion.
Name some examples of alloys.
Brass = copper + zinc
Bronze = copper + tin
Stainless steel = iron, nickel + chromium
List the reactivity series in order of most reactive to least reactive.
Lithium - Li Potassium - K Calcium - Ca Sodium - Na Magnesium - Mg Aluminium - Al CARBON - C Zinc - Zn Iron - Fe Nickel - Ni Tin - Sn Lead - Pb HYDROGEN - H Copper - Cu Mercury - Hg Silver - Ag Gold - Au Platinum - Pt
List the metals in the reactivity series that exist as native metals.
- Silver
- Gold
- Platinum
What is an ‘ore’?
A rock containing enough of a metal compound for it to be worth extracting the metal from the rock.
What is ‘bauxite’?
Bauxite contains aluminium oxide
What is ‘hematite’?
Iron oxide
How do we extract metals that are more reactive than than carbon?
Electrolysis
Describe the use of carbon in the extraction of some metals.
Reduction with carbon.
- Used for oxides of metals less reactive than carbon - the carbon displaces the metal, stealing the oxygen to form carbon dioxide and leaving the metal. Carbon is used because it is cheap and plentiful.
Describe how iron is extracted from its ore in the blast furnace and the raw materials needed.
Raw materials: hematite, coke (carbon but with impurities), limestone and air.
- A strong current of air is blown in at the bottom of the furnace.
- Temp: between 250C at the top and 1500C at the bottom.
- Main reducing agent: carbon monoxide.
What are the essential reactions and the steps taken in extracting the iron?
- At the bottom of the furnace, the coke burns with hot air to form carbon dioxide (exothermic):
C(s) + O2(g) -> CO2(g) - The carbon dioxide reacts with the coke to form carbon monoxide:
CO2(g) + C(s) -> 2CO(g) - The carbon monoxide reduces the iron(III) oxide to iron:
Fe2O3(s) + 3CO(g) -> 2Fe(l) + 3CO2(g) - In hotter parts of the furnace, carbon reduces iron(III) oxide directly:
Fe2O3(s) + 3C(g) -> 2Fe(l) + 3CO(g)
Why is limestone needed in the extraction of iron?
Hematite contains sand (silicon(IV) oxide) as a major impurity. The limestone helps remove the impurity.
What are the chemical reactions needed for the removal of impurities in hematite by limestone?
- The heat decomposes the limestone:
CaCO3(s) -> CaO(s) + CO2(g) - The calcium oxide reacts with the silicon(IV) oxide to form a slag of calcium silicate:
CaO(s) + SiO2(s) -> CaSiO3(l)
Why is aluminium widely used in aircraft?
It is lightweight - it has a low density - and also quite strong.
What are the alloys made from aluminium that is used for aircraft?
Aluminium alloys contain 90% aluminium and smaller amounts of zinc and copper.
What is zinc used for?
Galvanise (coat) iron or mild steel to prevent rusting.
Why is aluminium used in food containers?
There is an unreactive oxide layer on its surface which does not flake off - does not react with acids that are present in many foods.
Resistant to corrosion.
