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Chemistry - Carbon Chemistry - Hydrocarbons (Alkanes and Alkenes) and polymers

Terms in this set (13)

LDPE is used to make plastic food wrap as it is un-reactive because all of its valence electrons are used up in covalent bonding so it is stable, which means that it will not react with the food in the wrap. It is also very flexible because the attractions between the long chains of joined monomers is weak so the chains can slide past each other. The chains are packed loosely together so it is easy to mould to fit around the food it is holding, it is also insoluble in water which is useful as it will not dissolve in water. Because it is un-reactive, flexible to fit around the found and light so it is easily stored and easy to mould - LDPE is used to make plastic food wrap.
HDPE is insoluble which means that it will not dissolve in the drink that is in holding. HDPE is less flexible than LDPE which is good as the bottle will be sturdy and able to properly hold the drink it was instead of bending. Its chains are packed more tightly together which shows that the individual molecules in HDPE are very strong and so are the attractive forces between the long molecules. This makes it tough and able to hold it shape and is useful to make into drink bottles. Its mass is also light as plastic drink bottles are not supposed to be difficult to carry. It is also un-reactive which is good because it means that the polythene bottle will not react with the substances inside it. Therefore, the HDPE is used to make drink bottles as it is not too flexible, un-reactive, insoluble, light and has tightly packed chains so is tougher than LDPE.