10 - Metals

10.1 Properties Of Metals

10.2 Metal Reactions

With Acid

-If a metal reacts with hydrogen and the metal chloride are produced

-You will notice effervescence

Magnesium +HCL -> Magnesium Chloride + Hydrogen

With air/oxygen

-Many metals react with oxygen to form oxides

Magnesium + 02 -> Magnesium Oxide

With cold water/steam

-Reactive metals such as potassium, sodium and calcium react with cold water to produce the metal hydroxide and hydrogen gas

-The moderately reactive metals, magnesium, zinc and iron react slowly with water

-They will, however react more rapidly with steam

-In their reaction with steam, the metal oxide and hydrogen are formed

Magnesium + Steam -> Magnesium Oxide + Hydrogen

Displacement Reactions

-Metals compete with each other for other anions, in solution

-This type of reaction is known as a displacement reaction

-In a displacement reaction, a more reactive metal will displace a less reactive metal from a solution of its salt

Zinc + copper (II) nitrate -> Zinc Nitrate + Copper

The ionic equation for this reaction is:

Zinc + copper ions -> Zinc ions + Copper

10.4 - Refer Coursebook

10.5 - Extraction of Metals

Extraction Of Iron

-Iron is extracted mainly from its oxides, hematite (Fe2O3) and magnetite (Fe304), in a blast furnace

-These ores contain at least 60% iron

-The blast furnace is a steel tower, approx. 50m high, lined with heat-resistant bricks

-It is loaded with the 'charge' of iron ore 9usually hematite), carbon in the form of coke (made by heating coal) and limestone (Calcium carbonate)

-Refer Coursebook

10.6 Metal Corrosion

-Rusting of iron and steel to form hydrated iron (II) oxide requires both water and oxygen

Rust Prevention

Painting (for iron and steel structures such as ships, cars, lorries and buses)

-If the paint is scratched, the iron beneath it will start to rust and corrosion can then spread under the paintwork which is still sound

Oiling/greasing (for iron and steel structures such as machinery)

-The iron and steel parts are coated with oil to prevent them from coming into contact with air or moisture

However, the protective film must be renewed

Coating with plastic

-The exteriors of refrigerators, freezers and many other items are coated with plastic, such as PVC, to prevent the steel structure rusting

Galvanising (for steel beams used in the construction of bridges and buildings)

-This involves dipping the object into molten zinc

-The thin layer of the more reactive zinc metal coating the steel object slowly corrodes and loses electrons to thee iron, thereby protecting it

-This process continues even when much of the layer of zinc has been scratched away, so the iron continues to be protected

Corrosion

-Rusting is the most common form of corrosion but it is confined to iron and steel

-Name given to the process which takes place when metals and alloys are chemically attacked by oxygen, water or any other substances found in their immediate environment

-Generally, the higher the metal is in the reactivity series, the more rapidly it will corrode

Alloys

-Refer Coursebook