Page 13 - Curriculum Visions Dynamic Book

 A representation of a urea molecule.
Hydrogen
Nitrogen
Oxygen
Carbon
alkaline: the opposite of acidic. Alkalis are bases that dissolve, and alkaline materials are called basic materials. Solutions of alkalis have a pH greater than 7.0 because they contain relatively few hydrogen ions.
resin: natural or synthetic polymers that can be moulded into solid objects or spun into thread.
soluble: a substance that will readily dissolve in a solvent.
 The TransAlaskan pipeline uses refrigeration by ammonia in the thousands of legs that support the pipeline over permafrost areas. The refrigerated legs are needed to prevent the permafrost from melting, allowing the legs to founder and causing the pipeline to fracture.
Uses of ammonia
About three-quarters of the ammonia produced is used to make fertilisers. It can be sprayed on crops, on the ground or injected as a gas into the soil. Because it is so soluble it can also be readily added to irrigation water.
Ammonia is also a starting material for a substance called urea, CO(NH2)2, which is used as a fertiliser in its own right and also in the manufacture of resins, some cosmetics, and medicines.
If ammonia is not used directly as a fertiliser, it is mainly converted to ammonium nitrate, by reacting ammonia with nitric acid. Ammonium nitrate can also be used in explosives such as TNT and dynamite (see page 27).
Ammonium chloride is used as a cleaning agent for metals prior to their being painted, galvanised or soldered. Ammonium chloride is also found in the paste inside all zinc–carbon dry cells.
Ammonia is also used by some craftspeople because, when soaked into wood, it makes the wood behave as
a plastic which can then be shaped. As the ammonia evaporates, the wood again becomes hard.
EQUATION: Reaction of ammonia and nitric acid
Ammonia + nitric acid ➪ ammonium nitrate NH3(aq) + HNO3(aq) ➪ NH4NO3(aq)
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