Production of Materials - POLYMERS Flashcards

Question

Hydration of alkenes

Answer 1

* addition of H₂O * often used to produce ethanol from ethene * requires acid catalyst [usually dilute H₂SO₄ solution] * used in industry to produce alcohols, cosmetics and medicines * to maximise yield, ethene is reacted with water at high temp. [approx 300°C] and high pressure and use phosphoric acid [H₃PO₄] as catalyst * ethanol is a fuel additive and used in thermometers

Answer 2

* addition of H_{2 (g)} * requires a metal catalyst [usually Pt or Ni - do not take part in the reaction} - this catalyst is heated to 150°C * the basis for producing margarine * from vegetable oils [from double to single bonds - saturates] * this causes oils to harden into soft solids

Answer 3

* the addition of halogen * no need for catalyst as both alkene and halogen are reactive * example - 1,2 - dichloroethane [refrigerant and aerosol propellant]

Answer 4

* addition of hydrogen and halogen * examples: * HF [strongest acid] → flouroalkane * HCl → chloroalkane * HBr → bromoalkane * bromoethane is an industrial solvent

Answer 5

* addition of potassium permanganate [KMnO_{4 (aq)}] * very strong oxidising agent and very reactive * oxidation of ethene equation is as follows:

Answer 6

* making polymers [plastics] * polymer: a long chain molecule made up of repeating units [monomers] * ethene is the starting point for many polymers

Answer 7

* initiation: * requires a catalyst [organic peroxide] to break the double bond in the monomer * forms free radicals [highly reactive due to the unpaired electrons] * propogation: * monomers attach to carbon chain at free radicals * termination: * no more monomers can be added to polymer chain * formation of polymer

Answer 8

shown with the following structural equation:

Answer 9

shown with the following structural equation:

Answer 10

the final polymer product is shown as:

Answer 11

* can be low or high density PE * produced using addition polymerisation

Answer 12

* low density polyethylene * still use I.P.T. process * catalyst - organic peroxide * conditions: * 100-300°C * very high pressure [1500-3000 atmosphere] * this decreases volume and increases collision frequency of free radicals thereby increasing the yield of polymer * structure: * tends to have shorter polymer chains with lots of side branches [up to 5 C atoms] * side branches prevent close packing of chains therefore _low_ density * same formula = [C₂H₄]_n * properties: * tough * brittle * flexible * semi-crystalline [lots of spacing and low density areas] * transparent/transluscent * very pure compound * not heat resistant * uses: * gladwrap * plastic bags * tupperware

Answer 13

* high density polyethylene * still use I.P.T. * catalyst - zeigler-natta [Al based oxide] * conditions: * optimum is 300°C * low pressure [1-2 atmosphere] * structure: * long, linear chains with very few or no side chains therefore when cooled, the molecules pack closer together therefore _high_ density * same formula - [C₂H₄]_n * properties: * very strong * less flexible * less transparent [often appears white] * does contain some impuities [zeigler-natta partially breaks down] * heat resistant [\>100°C] * uses: * oven bags * kitchen electrical appliances * water pipes * buckets * wheelie bins * petrol tanks

Answer 14

* monomer: chloroethene [vinyl chloride] * undergoes addition polymerisation

Answer 15

* monomer: ethenylbenzene [styrene] * undergoes addition polymerisation

Answer 16

* monomer: tetrafloroethene * undergoes addition polymerisation * polymer has an almost frictionless surface * used in non-stick fry pans, greaseless bearings etc.

Answer 17

* usually requires two separate monomers * a condensation polymer forms by the elimination of a small molecule [usually H₂O] when pairs of monomer molecules join together * cellulose is a naturally occurring condensation polymer which is formed from the monomer unit glucose

Answer 18

* C₆H₁₂O₆ * carbohydrate in which the atoms are arranged in a ring [arranged as seen in image] * the presence of five hydroxyl groups allows the polymerisation of glucose to form cellulose, starch and glycogen * the 'backbone' of polymers is formed by the elimination of water [H₂O] between C¹ of one glucose molecule and C⁴ of another

Answer 19

* monomer: glucose [C₆H₁₂O₆] - ring carbohydrate * undegoes condensation polymerisation * the elimination of water occurs between C¹ of one glucose molecule and C⁴ of another * polymer contains 1800-3000 glucose units per molecule * fibre-like material - present as long chains packed close together * the polymer chains of cellulose lie parallel to the axis of the cellulose fibre * fibres are held together by strong H bonds [between H and OH groups * cotton fibres are 90% cellulose * rigid, strong, able to resist chemical attack and highly insoluble

Answer 20

* monomer: glucose [C₆H₁₂O₆] - ring carbohydrate * undergoes condensation polymerisation * the elimination of water occurs between C1 of one glucose molecule and C4 of another * fluffy, powdery material with numerous side chains * isn't as closely packed as cellulose * not very reactive [insoluble in cold water but soluble in hot water]

Answer 21

Natural: * starch * cellulose * rubber * cotton * silk Synthetic: * made from fossil fuels * polyethylene [PE] * polyvinylchloride [PVC] * polystyrene [PS] * Teflon * Kevlar * nylon

Answer 22

* decomposition process of glucose into ethanol * chemical equation for fermentation: C₆H₁₂O_{6 (aq)} → 2C₂H₅OH_(l) + 2CO_{2 (g)} * conditions necessary: * the substrate [glucose or succrose] being in solution * the presence of yeast [provides catalyst zymase] * an approx. temperature of 37°C [blood temp.] * the exclusion of air [anaerobic] * suitable pH * N.B. once the cocentration of ethanol reaches 14-15% the yeast can no longer survive therefore fermentation stops