A polymer model contains 150 chains. Each chain contains 400 repeat units.
.1
Calculate the total number of repeat units represented.
[2 marks].2
Explain why this model represents a polymer rather than a giant covalent lattice.
[2 marks]OCR Gateway GCSE Chemistry June 2018 Paper 4
5 questions on this paper's topics
30:001 of 5
Dilute hydrochloric acid is added to excess copper oxide. The black oxide becomes a blue-green copper chloride solution, with black solid remaining.
.1
Write the balanced equation.
[2 marks].2
Explain why excess copper oxide is used and how it is removed.
[2 marks].3
Explain why the mass of wet crystals would overestimate the mass of salt recovered.
[2 marks]Two separate samples each have mass 8.0 g. One is oxygen gas, , and the other is sulfur dioxide, . : O = 16, S = 32.
.1
Calculate the amount of oxygen molecules in the oxygen sample.
[2 marks].2
Calculate the amount of sulfur dioxide molecules in its sample.
[2 marks].3
Explain which sample contains more molecules and by what factor.
[2 marks]Students compare two catalysts for the decomposition of hydrogen peroxide. Each trial lasts 60 s; the same solution volume and concentration are available.
Plan an investigation to compare the rates fairly and assess whether a catalyst is used up.
[6 marks]A town collects 12 tonnes of glass. Sorting removes 8% as contamination. All remaining glass can replace virgin glass material in this simplified model.
.1
Calculate the mass available to replace virgin material.
[2 marks].2
Explain why reducing packaging use can give benefits beyond recycling the same mass.
[2 marks]