Edexcel Jan 2012 Paper 1 Q22 (with explained solutions) |

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Edexcel Jan 2012 Paper 1 Q22

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PMT 22 (a) State how the following processes are achieved in a mass spectrometer. (i) Ionization of the sample. (1)(ii) Acceleration of the ions. (1)(iii) Deflection of the ions. (1)(b) State how you could find the molecular mass of a substance from its mass spectrum. (1)(cid:3) (cid:11)(cid:70)(cid:12)(cid:3)(cid:47)(cid:76)(cid:89)(cid:76)(cid:81)(cid:74)(cid:3)(cid:87)(cid:75)(cid:76)(cid:81)(cid:74)(cid:86)(cid:3)(cid:87)(cid:68)(cid:78)(cid:72)(cid:3)(cid:88)(cid:83)(cid:3)(cid:87)(cid:75)(cid:72)(cid:3)(cid:85)(cid:68)(cid:71)(cid:76)(cid:82)(cid:68)(cid:70)(cid:87)(cid:76)(cid:89)(cid:72)(cid:3)(cid:76)(cid:86)(cid:82)(cid:87)(cid:82)(cid:83)(cid:72)(cid:3)(cid:70)(cid:68)(cid:85)(cid:69)(cid:82)(cid:81)(cid:16)(cid:20)(cid:23)(cid:3)(cid:73)(cid:85)(cid:82)(cid:80)(cid:3)(cid:87)(cid:75)(cid:72)(cid:3)(cid:68)(cid:87)(cid:80)(cid:82)(cid:86)(cid:83)(cid:75)(cid:72)(cid:85)(cid:72)(cid:17)(cid:3)(cid:3) In recent years a particular linen cloth was shown, using mass spectrometry, to have been made from flax grown in the early 14th century. Suggest how mass spectrometry can be used to estimate the age of the cloth. (2)(Total for Question 22 = 6 marks) *P39295A01524* 15 Turn over<br />

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Mark Reject High-density electrons Acceptable Answers Question Number 22(a)(i) The mark is for the idea of impact by high energy electrons Any ONE of: High-energy electrons Bombard with electrons Fast electrons (fired at sample) Accelerated electrons (fired at sample) (High-energy) electrons fired (at sample) (Sample) blasted with electrons Electron gun ALLOW beam of electrons IGNORE any comments (correct or incorrect) re subsequent ionization of the sample Acceptable Answers Question Number 22(a)(ii) Electric field /electrostatic field / charged plates /voltage plates Question Number 22(a)(iii) Magnetic field/magnet / Acceptable Answers electromagnet /magnetic plates/ electromagnetic field Mark Mark Reject Positively- charged plates /electronic field /electric current /(electro) magnetic field / electric coil Reject Negative magnetic field/ negatively- charged magnet 6CH0101 1201<br />
Question Number 22(b) Question Number 22(c) Mark Acceptable Answers Reject (Molecular mass of a substance is) that of the molecular ion/parent ion OR (m/e value for) peak/ion of largest mass OR (m/e value for) peak/ion furthest to the right ALLOW last peak/peak at the end Highest peak/ tallest peak/ comments about determination of relative atomic mass Acceptable Answers Reject Mark Mark independently: First mark: Any mention of (determination of) amount /mass/abundance of 14C (in cloth) ALLOW Any mention of (determination of) concentration/content/percentage of 14C (in cloth) OR find proportion of 12C : 14C (in cloth) (1) Second mark: Any mention of any one of the following:- (Use) half-life of 14C / mention that amount of 14C (in cloth) decreases (over time) / 14C decays over time / comparison of amount of 14C in living systems / comparison of amount of 14C in modern materials / compare with 12C : 14C in living systems (1) amount of 14C (in cloth) increases (over time) 6CH0101 1201<br />

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