Polymers (OCR A Level Chemistry A): Flashcards
Exam code: H432
1/160Still learning
Know0
Define condensation polymerisation
Was this flashcard helpful?
Cards in this collection (16)
Define condensation polymerisation
A condensation polymerisation is a type of polymerisation where monomers join together by repeated condensation reactions, eliminating a small molecule such as water.
Define repeat unit
A repeat unit is the smallest group of atoms that, when connected repeatedly, makes up the polymer chain, represented in square brackets.
What type of bond links monomers in a polyester?
Monomers in a polyester are linked by ester bonds, formed between a dicarboxylic acid and a diol.
How does the repeat unit of an addition polymer differ from its monomer?
The repeat unit is the same as the monomer except that the C=C double bond is replaced by a C-C single bond.
A polyamide is formed from a .......... and a .......... joined by amide bonds.
A polyamide is formed from a diamine and a dicarboxylic acid joined by amide bonds.
In a condensation polymer, the presence of an .......... link indicates the polymer is a polyester.
In a condensation polymer, the presence of an ester link indicates the polymer is a polyester.
Why can a single hydroxycarboxylic acid monomer form a polyester without a second monomer?
A hydroxycarboxylic acid contains both an alcohol group (-OH) and a carboxylic acid group (-COOH), so it can react with itself repeatedly to form ester bonds.
How can you identify whether a polymer was formed by addition or condensation polymerisation from its structure?
An uninterrupted chain of carbon atoms indicates addition polymerisation, while the presence of ester or amide links indicates condensation polymerisation.
True or False?
Condensation polymers can be identified by the presence of ester or amide bonds between monomers.
True.
Condensation polymers are characterised by ester or amide bonds linking their repeating units.
True or False?
The repeat unit of poly(ethene) contains a C=C double bond.
False.
In poly(ethene), the C=C double bond of the monomer opens during polymerisation, so the repeat unit contains only a C-C single bond.
Why are proteins classed as condensation polymers?
Proteins are formed by repeated condensation reactions between amino acids, with each linkage forming an amide bond and expelling a water molecule.
Why must you identify the repeat unit before finding the monomer of an addition polymer?
The repeat unit contains exactly two carbons in the main chain, which allows the original monomer with its C=C bond to be correctly deduced.
True or False?
A dioyl dichloride can be used instead of a dicarboxylic acid to form a polyamide.
True.
Dioyl dichlorides contain two -COCl groups and react with a diamine to form amide bonds, though they are more expensive than dicarboxylic acids.
True or False?
An amide link in a polymer structure is evidence of condensation polymerisation.
True.
An amide link is formed when a diamine reacts with a dicarboxylic acid or dioyl dichloride during condensation polymerisation to make a polyamide.
What are the products of acid and alkaline hydrolysis of a polyester?
Acid hydrolysis produces the original diol and dicarboxylic acid. Alkaline hydrolysis produces the diol and the sodium salt of the dicarboxylic acid (e.g. heating PET with HCl or NaOH respectively).
What are the products of acid and alkaline hydrolysis of a polyamide?
Acid hydrolysis produces a dicarboxylic acid and ammonium ions (NH4+). Alkaline hydrolysis produces the diamine and the sodium salt of the dicarboxylic acid.
Sign up to unlock flashcards
or