Shredded waste containing poly(propene) and poly(ethene) must be sorted before recycling. The density of poly(propene) is 0.90 g cm−30.90\,\mathrm{g\,cm^{-3}}0.90gcm−3 and the density of poly(ethene) is 0.95 g cm−30.95\,\mathrm{g\,cm^{-3}}0.95gcm−3.
Which liquid would separate the two polymers, and which polymer would float?
A liquid of density 0.92 g cm−30.92\,\mathrm{g\,cm^{-3}}0.92gcm−3; poly(propene) floats
A liquid of density 0.92 g cm−30.92\,\mathrm{g\,cm^{-3}}0.92gcm−3; poly(ethene) floats
Water, of density 1.00 g cm−31.00\,\mathrm{g\,cm^{-3}}1.00gcm−3; poly(propene) floats
A liquid of density 0.85 g cm−30.85\,\mathrm{g\,cm^{-3}}0.85gcm−3; poly(ethene) floats
37 exam-style questions on Edexcel GCSE Chemistry 10.3 Polymers, covering 10.3.1 Addition polymerisation of alkenes, 10.3.2 Uses and properties of polymers, 10.3.3 Condensation polymers and polyesters, 10.3.4 Problems with polymers and recycling, and 10.3.5 Natural polymers: DNA, starch and proteins. Each one has a worked solution and a mark scheme showing where the marks go.