MDCAT Chemistry · Chemistry · Industrial chemistry. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
Plants need nitrogen and phosphorus in forms that dissolve in water. Nitrogenous fertilisers, such as urea and ammonium nitrate, are made from ammonia. Phosphatic fertilisers are made from rock phosphate, Ca3(PO4)2, which is almost insoluble. Treating it with acid changes it into soluble calcium dihydrogenphosphate, Ca(H2PO4)2.
Crude petroleum is a mixture of hydrocarbons. Refining separates it by fractional distillation into fractions with different boiling ranges. Cracking then breaks large molecules into the smaller ones needed for petrol, and gives alkenes as well.
Alkenes from cracking, mainly ethene, are the starting materials for plastics and many other petrochemicals.
Students mix up cracking and reforming. Cracking makes molecules smaller to give more petrol and alkenes; reforming keeps the number of carbon atoms about the same but changes the shape of the molecule to raise the octane number.
Answer: 35% nitrogen by mass
Type what you are stuck on. The helper finds the explanation, worked examples and the notes to read, free and instant.