Skip to content
CIE Nov 2014 v1 Paper 2 Q1
Answers available below
Show answer
Question
1
2
3
4
![Answer all the questions in the spaces provided. (a) Successive ionisation energies for the elements magnesium to barium are given in the table. PMT element 1st ionisation energy / kJ mol1 2nd ionisation energy / kJ mol1 3rd ionisation energy / kJ mol1 Mg Ca Sr Ba 736 590 548 502 1450 1150 1060 966 7740 4940 4120 3390 (i) Explain why therst ionisation energies decrease down the group.[3] (ii) Explain why, for each element, there is a large increase between the 2nd and 3rd ionisation energies.[2] (b) A sample of strontium, atomic number 38, gave the mass spectrum shown. The percentage abundances are given above each peak. 100 percentage abundance 82.58 80 81 82 83 0.56 84 9.86 7.007.00 85 86 87 88 89 90 atomic mass unitsUCLES 2014 9701/21/O/N/14<br />
PMT (i) Complete the full electronic con guration of strontium. 1s2 2s2 2p6[1] (ii) Explain why there are four different peaks in the mass spectrum of strontium.[1] (iii) Calculate the atomic mass, Ar, of this sample of strontium. Give your answer to three signi cantgures. Ar =[2] (c) A compound of barium, A, is used inreworks as an oxidising agent and to produce a green colour. (i) Explain, in terms of electron transfer, what is meant by the term oxidising agent.[1] (ii) A has the following percentage composition by mass: Ba, 45.1; Cl , 23.4; O, 31.5. Calculate the empirical formula of A. empirical formula of A[3]UCLES 2014 9701/21/O/N/14 [Turn over<br />
(d) Some reactions involving magnesium and its compounds are shown in the reaction scheme below. X(aq) water Mg(s) steam Y(s) PMT HNO3(aq) reaction reaction Z(aq) Z(s) (i) Give the formulae of the compounds X, Y and Z. XYZ[3] (ii) Name the reagent needed to convert Y(s) into Z(aq) in reaction 1 and write an equation for the reaction. reagentequation[2] (iii) How would you convert a sample of Z(s) into Y(s) in reaction 2?[1] (iv) Give equations for the conversions of Mg into X, and Z(s) into Y. Mg to XZ to Y[2] [Total: 21]UCLES 2014 9701/21/O/N/14<br />
PMT Question 2 starts on the next page.UCLES 2014 9701/21/O/N/14 [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/November_2014_v1_QP_-_Paper_2_CIE_Chemistry_A-level_1-0.jpg)
![Page 2 Mark Scheme Syllabus Paper Cambridge International AS/A LevelOctober/November 2014 9701 21 Question Mark Scheme (a) (i) increasing distance of (outer) electron(s) from nucleus OR increasing distance of outer / valence shell from nucleus increased shielding / screening (from inner shells) reduces attraction (ii) (b) (i) electron for each in) inner / lower energy level / shell / closer to nucleus rd (3 (than first two) / less shielding (large) increase in nuclear attraction 6 2 6 2 2 (1s 2s 2p ) 3s 3p 3d 10 2 6 2 4s 4p 5s (ii) four isotopes owtte (840.56) + (86 9.86) + (87 7)(88 82.58) (iii) = 87.7 (must be 3 sig figs) 100 (c) (i) (a species that) gains / takes electron(s)Cambridge International Examinations 2014 Marks Total 1 1 1 1 1 [3] [2] [1] [1] [2] [1]<br />
Page 3 Mark Scheme Syllabus Paper Cambridge International AS/A LevelOctober/November 2014 9701 21 Question Mark Scheme (ii) Ba Cl 45.1 137 23.4 35.5 31.5 16 0.329 0.329 0.659 0.329 1.969 0.329 1.00 2.00 5.98 / 6 emp form = BaCl2O6 (d) (i) X = Mg(OH)2 Y = MgO Z = Mg(NO3)2 (ii) reagent = nitric acid MgO + 2HNO3Mg(NO3)2 + H2O (iii) Heat / thermal decomposition (iv) Mg + 2H2OMg(OH)2 + H2 2Mg(NO3)22MgO + 4NO2 + O2Cambridge International Examinations 2014 Marks Total 1 1 1 1 1 1 1 [3] [3] [2] [1] [2] [21]<br />](https://learnah.org/wp-content/uploads/2018/08/November_2014_v1_MS_-_Paper_2_CIE_Chemistry_A-level_1-0.jpg)
