chapter 13 Flashcards
cracking
large hydrocarbons broken down to produce smaller, more useful molecules. This process involved heating the hydrocarbons to vaporise them. The vapors are either passed over a hot catalyst or mixed with stea, and heated to a very high temperature so that thermal decomposition reactions occur
products of cracking
-alkanes
-alkense
alkenes with bromine water
orange to colorless
polymerization
when monomers form polymers
different reaction condintions in polymerization
-Using very high pressures and trace of oxygen. ethene forms LD polyethene
-using a catalyst at 50 degrees and a slightly raised pressure, ethene makes HD polyethene
thermosetting polymers
-consist of polymer chains with cross kinks between them so they dont melt when heated
-their monomers make covalent bonds between the polymer chains when they are first heated in order to shape them
-these covalent bonds are strong, and they stop the polymer from softening
-the covalent ‘cross links’ between chains do not allow them to seperate
-even is heated strongly, the polymer will still not soften
-eventually the polymer will char at high enough temperatures
thermosoftening polymers
-consist of individual,tangled polymer chains
-forces between polymer chains are weak
-when the polymer is heated, these weak intermolecular forces becomes soft
-when the polymer cools down, the intermolecular forces bring the polymer molecules back together
-then the polymer hardens, this type of polymer can be remolded
polymer uses
-new packaging material
-waterproof coating for fabrics
-dental polymers
-wound dressing
-hydrogels
-smart materials (including shape memory polymers)
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plastic bags are being made from…
polymers and cornstartch so that they breakdown more easily
what do non- biodegradable polymers causes
-take up space in landfill sites
-harm wildlife
-unsightful rubbish
