Ch 20 - (Petrochemicals) Flashcards
What are polymers?
- Large molecules built by linking 50 or more smaller molecules called monomers
- repeat unit is connected to adjacent unit via covalent bonds
What is an example of polymer?
PVC and nylon
how is poly (ethene) formed?
Addition polymerization of ethene monomers
What does addition of polymerization involve?
- Addition of many monomers to make a long chained polymer
- Many ethene monomers join together due to carbon carbon double bond breaking (C = C)
Explain the addition of polymers.
- Joins up many monomers with (C = C) bond
- one of the bonds in C=C breaks and forms a bond with the adjacent monomer
- polymer contains single bonds
What are some other polymers made of?
- Addition of alkene monomers
- alkene monomers with different atoms attached to the monomer such as chlorine or a hydroxyl group.
How is the name of a polymer deduced?
- name of the monomer in bracket
- adding poly - as prefix
- If propene is the alkene monomer used, same is poly (propene)
- poly ethene formed by addition of polymerization of ethene monomers
How are polymer molecules?
Very large compared to most molecules
What is used to display formula of polymers?
repeat units
How do we draw a repeat unti?
- change the double bond in monomer to a single bond
- add a continuation bond to each end of repeat unit
- bonds on either side of polymer must be extended outside the brackets (called extensions or continuation bonds)
- small subscript n is written on bottom right hand side to indicate large number of repeat units
- Add on rest of the group in same order
How do we deduce the monomer from the polymer?
- identify the repeating unit polymer
- change single bond in repeat unit to a double bond in monomer
- remove bond from each end of repeat unit
How is condensation polymer formed?
2 different monomers are linked together with the removal of a small molecule, usually water
Hat is the difference between condensation polymer and addition polymer?
- addition polymerization forms the polymer molecule only
- condensation polymerization forms the polymer molecule and one water molecule per linkage
What do monomers have?
- 2 functional groups, one on each end
- each monomer react with another end of monomer, creating a long chain of monomers
What is a nylon?
- polyamide made from dicarboxylic acid (carboxylic with COOH group on either side)
- diamines (an amine with NH2 group at either end)
How is nylon polymer formed?
Each COOH group reacts with another NH2 group on other monomers
How is an amide linkage formed?
formed with a subsequent loss of one water molecule per link
How is the structure of nylon represented?
drawing out the polymer using boxes to represent the carbon chain
What is PET?
- polyethylene terephthalate
- polyester made up of dicarboxylic acid monomers (COOH group at either end) and diols (alcohols with OH group at either end)
How is PET polymer formed?
each COOH group reacts with another OH group on another monomer
How is an ester linkage formed?
- subsequent loss of one water molecule per link
- every ester linkage formed in condensation polymerization, one molecule of water is formed from the combination of a proton (H+) and hydroxyl ion (OH-)
What is PET used in?
synthetic fibres sold under terylene
How is the structure of PET represented?
drawing out polymer using boxes to represent carbon chain
What is plastic made up of?
- Polymer
- chemically uncreative (non - biodegradable)
How is incineration caused due to polymers being burnt?
- release heat energy
- produce CO2 (greenhouse gases)
- contributes to climate change
- release toxic fumes when burnt
- incinerated by incomplete combustion, carbon monoxide will be produced in a toxic gas
What issues are caused due to polymer disposal?
- Polluting oceans
- Landfills
What happens in polluting oceans when polymers are disposed?
Plastic accumulated in oceans causing huge disruption to marine
What happens in landfills when polymers are disposed?
- sites fill up quickly
- take up valuable land
What is PET (polyethylene terephthalate) used to make?
used to make plastic bottles
What happens in condensation polymer with re - polymerisation?
- consisting of repeating ester units
What are the conditions needed to recycle polymers?
Conditions:
- High pressures
- High temp
- degrade monomers making them re usable
How is PET re - polymerised?
- easy to convert to monomers
- depolymerized using enzyme or chemical methods
- enzymes in microbes breakdown PET into original monomers
- same is achieved using solvents a mild catalyst and heating
- monomers are recovered and are re - polymerized into new PET
- saves on energy and resources
What are proteins?
Example of condensation polymers
How are proteins formed?
- from amino acid monomers joined together by amide links
- amino acids contain NH2 and COOH functional groups
What are proteins also known as and why?
- due to containing amide links
- found in biological systems
- known as natural polyamides
- in protein the amide links are shown as peptide
How is the structure in proteins?
- twenty common amino acids
- differing by side chain, represented by R
How can the protein structure be represented?
boxes represent the carbon chain
