chapter 13

Question 1

cracking

Answer 1

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

Question 2

products of cracking

Answer 2

-alkanes
-alkense

Question 3

alkenes with bromine water

Answer 3

orange to colorless

Question 4

polymerization

Answer 4

when monomers form polymers

Question 5

different reaction condintions in polymerization

Answer 5

-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

Question 6

thermosetting polymers

Answer 6

-consist of polymer chains with cross links 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

Question 7

thermosoftening polymers

Answer 7

-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

Question 8

polymer uses

Answer 8

-new packaging material
-waterproof coating for fabrics
-dental polymers
-wound dressing
-hydrogels
-smart materials (including shape memory polymers)
-

Question 9

plastic bags are being made from…

Answer 9

polymers and cornstartch so that they breakdown more easily

Question 10

what do non- biodegradable polymers causes

Answer 10

-take up space in landfill sites
-harm wildlife
-unsightful rubbish