Thermal Decomposition

All Saints 2006

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
   Ca      CaC      Calcium Silicate      Carbon Dioxide      catalyst      Copper Oxide      decompose      decomposition      dehydration      Endothermic      fuels      heated      limestone      molecules      Oxide      polythene      raising      Sodium Hydrogen Carbonate      stalagmites      water      Water   
Most metal carbonates, and metal hydroxides when .
Examples :-

Copper Carbonate (CuCO3(s)) -->Copper (CuO(s))+ (CO2(g))

Copper Hydroxide (Cu(OH)2(s)) --> (CuO(s)) + (H2O(g))
This loss of water by Copper Hydroxide is called .

Thermal decomposition of Calcium Carbonate, Limestone (CaCO3) is important because it is used on a massive scale in the production of quicklime (CaO) and Cement (Heat limestone with Clay). Glass is also made by heating (CaCO3), but in this case it is with sand(SiO2), the reaction products are Calcium Silicate + carbon dioxide. Glass is thus , although there are many addatives in most modern glass.

Thermal decomposition reactions need to be heated because thay are reactions, this means that they need to take in heat when the reaction to takes place. As a contrast when quicklime comes in contact with any water it reacts with a very stong Exothermic reaction to become slaked lime, Calcium Hydroxide (Ca(OH)2).

Group 1 (One) Metals behave differently Heat does NOT them. Goup 1 carbonates are MADE by themal of Metal Hydrogen Carbonates Example:-

Sodium Hydrogen Carbonate (NaHCO3(s))-->Sodium Carbonate (Na2CO3(s)) + Carbon Dioxide (CO2(g))
+ Water (H2O(g)). This reaction is used in cooking, (sometimes called sodium Bicarbonate) is a major part of most baking powders. It is thus also put into plain flour to make self flour.

Other Metal Hydrogen Carbonates behave in a simular way. Water that is found in area's that have lots of limestone often have Calcium Hydrogen carbonate disolved in it. When 'Hard ' is boiled, Calcium Hydrogen carbonate decomposes to leave limescale behind.
Example:-
Calcium Hydrogen carbonate decomposes to Calcium Carbonate + +.
(HCO3)2(aq))--> O3(s)+(CO2(g))+ (H2O(g))
It is this same reaction that slowly forms stalactites and in caves.

Thermal decomposition is also used in the petrolium industry.
Crude oil does not contain enough smaller hydrocarbon such as octane (C8H18) for the demand. Therefore larger hydrocarbon molecules are 'Cracked' into smaller ALKANES such as ethane. butane, propane, hexane etc., used as and ALKENES such as ethene, propene etc, used to make plastics polyethene, also known as . This Cracking process is speeded up and happens at lower temperatures by using a . This is called Cat Cracking.