OCR A Jun 2016 Paper 2 Q6 (with explained solutions) |

Skip to content

OCR A Jun 2016 Paper 2 Q6

Answers available below

18 This question is about several unsaturated hydrocarbons. (a) The mass spectrum of an alkene is shown below. 100 relative intensity 80 60 40 20 II 10 20 30 40 50 m / z 60 70 80 (i) The empirical formula of the alkene is CH2. Use the empirical formula and the mass spectrum to confirm the molecular formula as C6H12.[1]OCR 2016<br />
(ii) Further analysis showed that the alkene was hex-2-ene. 19 Suggest possible structures for the species responsible for the labelled peaks I and II in the mass spectrum of hex-2-ene shown opposite. peak I peak II (b) Hex-2-ene shows E/Z isomerism. (i) Draw the skeletal formulae of E-hex-2-ene and Z-hex-2-ene. [3] [2] E-hex-2-ene Z-hex-2-ene (ii) State and explain the features of a hex-2-ene molecule that lead to E and Z isomers.[2] Turn overOCR 2016<br />
(c) A section of a polymer that can be made from an unsaturated hydrocarbon B is shown below. 20 (i) Add brackets to the section of the polymer to show one repeat unit. [1] (ii) Draw the structure of hydrocarbon B. (iii) The polymer has a relative molecular mass of 50,000. Calculate the number of monomer molecules required to make one molecule of the polymer. [1] number of monomer molecules =[1] [Total: 11]OCR 2016<br />

Show answer

F322 Question (a) (i) Evidence that 84 (M+ peak) Answer (a) (ii) 84 = 6 14 = 614 (mass of CH2) (cid:57) e.g. Structures of species peak I CH3CH=CH (cid:57) peak II CH3CH=CHCH2CH2 OR CH=CHCH2CH2CH3 (cid:57) 2 marks + charge on BOTH CORRECT species CH3CH=CH+ AND CH3CH=CHCH2CH2 peak II peak I 1 mark + (cid:57) Mark scheme June 2016 Marks Guidance IGNORE use of molecular formula e.g (612) + (121) = 84 (use of empirical formula required) ALLOW correct structural OR displayed OR skeletal formula OR mixture of the above ALLOW 1 mark if both correct structures are shown but in the incorrect columns ALLOW 1 mark for both correct structures if one or both have an end bond ALLOW 1 mark for BOTH molecular formulae correct C3H5 peak I AND C5H9 peak II ALLOW charge mark for + charge on BOTH fragments with correct molecular formulae ALLOW charge mark for + charge on BOTH CORRECT molecular formulae ALLOW + change anywhere in structures OR outside brackets 26<br />
F322 Question (i) (b) Mark scheme Marks Answer (cid:57) E-hex-2-ene Z-hex-2-ene (cid:57) (b) (ii) (c) (i) (carbon-carbon) double bond does not rotate OR has restricted rotation (cid:57) Each carbon atom of the double bond attached to (two) different groups/atoms (cid:57) June 2016 Guidance ALLOW 1 mark if skeletal formulae of both E and Z hex-2-ene are shown but in the incorrect columns IF correct unambiguous structural OR displayed OR mixture of formulae are shown ALLOW 1 mark if both stereoisomers are in the correct columns e.g the following scores 1 mark CH3 CH3 CH2CH2CH3 CH2CH2CH3 E-hex-2-ene Z-hex-2-ene IF the skeletal formula of E hex-3-ene is shown in the first box ALLOW 1 mark for the skeletal formula of Z hex-3-ene as ECF ALLOW repeat unit at any point along the section provided that it works, e.g. One repeat unit shown (cid:57) (could be any of the three repeat units shown) 27<br />
F322 Question (c) (ii) Structure of pent-2-ene: Answer Mark scheme Marks OR (cid:57) (50,000/70 =) 714 OR 715 (cid:57) (c) (iii) June 2016 Guidance ALLOW correct structural OR displayed OR skeletal formula OR mixture of the above (as long as unambiguous) MUST be a whole number Total 11 28<br />

Question 1 2 3 4 5 6 7

About us | Need Help? | Feedback

Proudly powered by WordPress | Theme: Sydney by aThemes.