20.1. Addition polymerisation
A subsection of Chemistry, 9701, through 20. Polymerisation
Listing 10 of 116 questions
Complete the equations to show the two types of polymerisation. Draw one repeat unit for each polymer. Include any other products. ● addition polymerisation n CH2=CHCH3● condensation polymerisation n HO2CCH2CO2H+ n HOCH2CH2OH Suggest the sign of the entropy changes, ΔS o, for each of the two types of polymerisation. Explain your answers. ● ΔS o for addition polymerisation ● ΔS o for condensation polymerisation  An amide bond forms when a carboxylic acid reacts with an amine. Complete the equation by writing the products in the box. R–CO2H + H2N–R' +  Use your answer to to work out the bonds that are broken and the bonds that are formed during the reaction between a carboxylic acid and an amine. ● ● bonds that are broken ● ● bonds that are formed  Use bond energy values from the Data Booklet to calculate the enthalpy change, ΔH o, when one mole of amide bonds is formed in the reaction in . ΔH o = kJ Amide bonds can also be formed by reacting acyl chlorides with amines. The enthalpy change for this process, ΔH o, is – 6.00 kJ mol–1. Calculate the minimum entropy change, ΔS o, for this reaction to be spontaneous at 298 K. ΔS o = J K–1 mol–1 The repeat unit of the polyamide Kevlar is shown. O O N H N H The monomers of Kevlar, benzene-1,4-dioic acid and 1,4-diaminobenzene, can be synthesised as follows. H3C CH3 HO2C CO2H benzene-1,4-dioic acid reaction 1 O2N NO2 H2N NH2 1,4-diaminobenzene reaction 2 State the reagents and conditions needed for: reaction 1 reaction 2 Kevlar is both strong and rigid. Complete the table to identify two intermolecular forces and the groups involved which are responsible for these properties of Kevlar. intermolecular force groupinvolved  
9701_m18_qp_42
THEORY
2018
Paper 4, Variant 2
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The amino acids tyrosine, lysine and glycine are constituents of many proteins. State the reagents and conditions you could use to break proteins down into amino acids. Draw a ring around each chiral centre in the above molecules. In aqueous solution amino acids exist as zwitterions. Draw the zwitterionic structure of glycine. For each of the following reactions, draw the structure of the organic compound formed. glycine + excess NaOHtyrosine + excess NaOHUse CH2 C O CH OH tyrosine H2N OH (CH2)4 NH2 C O CH lysine H2N OH H C O CH glycine H2N OH [T lysine + excess HCltyrosine + excess Br2 Draw the structural formula of a tripeptide formed from all three of these amino acids, showing clearly the peptide bonds. The formula of part of the chain of a synthetic polyamide is shown below. Identify the repeat unit of the polymer by drawing square brackets around it on the above formula. Draw the structures of the two monomers from which the polymer could be made. CH2 CH2 CH2 NH NH NH CO CO CO CH2 CH2 NH NH CO
9701_s06_qp_4
THEORY
2006
Paper 4, Variant 0
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Spider silk is a natural polymer which has an exceptional strength for its weight. Kevlar is a man-made polymer designed to have similar properties. It has a wide variety of uses from sporting equipment to bullet-proof vests. C O H N H N O C N H C O O C N H O C Kevlar In Kevlar, the polymer strands line up to form strong sheets with bonds between the strands. On the diagram above, draw part of a second polymer chain showing how bonds could be formed between the chains. Suggest what type of bonds these are. Draw two possible monomer molecules for making the polymer Kevlar. The transport of oil by sea has resulted in a number of oil spills in recent years. As well as a waste of a valuable resource, these have caused major environmental problems. Traditional sorbent materials absorb water and sink. Researchers have developed new sorbent materials to help collect the spilled oil. The sorbent consists of a material called ‘hydrophobic aerogels’. This is a network of silicon(oxide with some of the silicon atoms attached to fluorine-containing groups. —O—Si—CH2—CF3 The introduction of these fluorine-containing groups allows the oil to be absorbed but not the water. Tests show that these materials can absorb more than 200 times their mass of oil without sinking. Suggest what the word hydrophobic means. Suggest why the fluorine-containing groups allow oil to pass through but not water molecules. Suggest another important fluorine-containing polymer that repels water-containing materials.
9701_s09_qp_4
THEORY
2009
Paper 4, Variant 0
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Describe and explain how the acidities of CHCl 2CO2H and CH2Cl CO2H compare to each other, and to the acidity of ethanoic acid. For each of the following pairs of compounds, suggest one chemical test (reagents and conditions) that would distinguish between them. State the observations you would make with each compound, writing ‘none’ if appropriate. fi rst compound second compound test (reagents and conditions) observation with fi rst compound observation with second compound NH2 NH2 CH3CH2COCl CH3COCH2Cl CH3CH2CHO CH3COCH3 The following diagram shows a section (not a repeat unit) of a polymer, G, that can be made from the two monomers E and F. O O O O O O O O polymer G E + F What type of polymerisation made this polymer? Draw the structures of the two monomers E and F. E F Suggest the conditions needed to make polymer G from E and F in the laboratory. One of the monomers, E or F, could be changed to make a more rigid polymer of a similar chemical type to G. Suggest which of your two monomers could be changed, and suggest a structure for the new monomer. Monomer to be changed (E or F) Structural formula of the new monomer
9701_s12_qp_42
THEORY
2012
Paper 4, Variant 2
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Questions Discovered
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