Thermal Decomp

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  • Created by: Najeeha
  • Created on: 22-05-14 22:16

Thermal Decomp

Thermal decomposition of Metal Carbonates

A number of metal carbonates can be thermally decomposed, including calcium carbonate, magnesium carbonate, lithium carbonate and...

CuCO3                          CuO + CO2

(green)                          (black)

ZnCO3                          ZnO + CO2

(white)                          (yellow when hot

                                    white when cold)

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Comp of Dry Air

Argon 0.9%

Nitrogen 78%

Oxygen 21%

Other gases including CO2 0.04%

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metals

Oxygen

Metals usually on heating are oxidised by reacting with oxygen in the air to produce metal oxide:

Acids 

Most metals react with acids forming a salt and hydrogen. Effervesence is observed as the reaction proceeds

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metals

Displacement Reactions of Metals 

More reactive metals displace less reactive metals from the compounds

Water

Reactive metals such as potassium,sodium and lithium react vigorously with water forming the metal hydroxide and hydrogen.

Sodium floats on water, moves over the surface of water and effervesces. In addition to these observations if potassium is used a lilac flame is observed. The reaction is highly exothermic causing the metal to melt and become spherical

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Reactivity series

Potassium

Sodium

Lithium

Calcium

Magnesium

Aluminum

Copper

Zinc

Hydrogen

Carbon

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Displacement

A very exothermic reaction is called a thermit reaction.

This is used to produce molten iron to join railway lines together. All displacement reactions are exothermic. The greater the difference in reactivity of the metal the more exothermic the reaction and the greater the tempertaure rise.

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