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Edexcel Jan 2015 (IAL) Paper 1 Q25
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![Acceptable Answers Question Number 25(a)(i) Mg+(g)Mg2+(g) + e() OR Mg+(g)e()Mg2+(g) OR Mg+(g) + e()Mg2+(g) + 2e() 1st mark Correct species for reactants and products (1) 2nd mark Correct state symbols This mark can only be awarded if first mark has already been awarded. (1) NOTE Award state symbols mark if X+(g) OR MG used instead of Mg Mg(g)Mg2+(g) + 2e() scores (0) Mark Reject MG for first mark WCH0101 1501<br />
Acceptable Answers Question Number 25(a)*(ii) Any TWO from: Electron (in Mg+) is being removed from a positive ion (1) Electron being removed is closer to the nucleus (in Mg+) / Mg+ is smaller (than Mg) (1) Proton: electron ratio greater (in Mg+) / remaining e more tightly held (in Mg+) (1) Greater (force of) attraction between nucleus and (outermost) electron (in Mg+) (1) Electron repulsion is less in Mg+ (than Mg) (1) IGNORE References to effective nuclear charge (ENC) / high charge-density in Mg+ / references to shielding Mark Reject Mg+ has more protons than Mg scores (0) overall Electron is being removed from a new shell/different shell / 2nd shell scores (0) overall Reject Mark WCH0101 1501 Question Number 25(a)(iii) Any value in range Acceptable Answers 5000 to 9000 (kJ mol1) NOTE Actual value is 7730 (kJ mol1)<br />
Reject Mark Reject Mark Acceptable Answers Question Number 25(b)(i) Question Number 25(b)(ii) 1st markidea of paired e in S Acceptable Answers (Phosphorus) 1s2 2s2 2p6 3s2 3p3 ALLOW px, py, pz notation / upper case (1) (Sulfur) 1s2 2s2 2p6 3s2 3p4 ALLOW px, py, pz notation / upper case (1) ALLOW Noble gas core: [Ne] for 1s2 2s2 2p6 In sulfur, spin-pairing has occurred / two electrons in the same orbital / paired e Note: Just 3p4 stated for S does not gain this mark. ALLOW an electrons-in-box diagram, showing two electrons in the same orbital (1) 2nd markidea of repulsion (resultant increase in) repulsion (1) ALLOW Just phosphorus has a half-filled sub- shell which is more stable (max (1)) (Total for Question 25 = 9 marks) TOTAL FOR SECTION B = 60 MARKS TOTAL FOR PAPER = 80 MARKS WCH0101 1501<br />](https://learnah.org/wp-content/uploads/2018/08/January_2015_IAL_MS_-_Unit_1_Edexcel_Chemistry_A-level_25-0.jpg)
