Final-exam-2009-solutions

Final-exam-2009-solutions - Name: _ Student Number: _...

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Name: ____________________________ Student Number: _______________ Version 1 Page 1 continued on next page…. CHEMISTRY 1E03 10 DECEMBER 2009 McMASTER UNIVERSITY - FINAL EXMINATION DURATION: 3 HOURS Instructor: J. Barbier ANSWERS FOR VERSION 1 QUESTIONS 1–25 ARE WORTH 2 MARKS EACH. 1. Identify the false statement(s): (i) (3, 2 , -1, -1/2) is an allowed set of quantum numbers for a 3d electron. (ii) The ground-state electron configuration of the sulfide anion (S 2- ) has two unpaired electrons. (iii) On average, a 3p electron in an Al atom is closer to the nucleus than a 3s electron. (iv) The (1s 2 2s 2 2p 6 3s 2 3p 1 ) electron configuration represents the ground state of the Si + cation. (v) The first ionization energy of potassium is smaller than that of sodium. A) ii, iii 2 mks B) i, iv C) iv, v D) v E) ii 1 mk 2. Select the true statement for the reaction of 15.0 g of magnesium metal and 5.00 g of nitrogen gas according to 3 Mg + N 2 Mg 3 N 2 A) Nitrogen gas is the limiting reagent and 5.00 g of Mg 3 N 2 is produced. 0.5 mk B) 20.8 g of Mg 3 N 2 is produced. C) There is no limiting reagent. D) There is an excess of 1.99 g of Mg. 2 mks E) Mg is the limiting reagent.
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Name: ____________________________ Student Number: _______________ Version 1 Page 2 continued on next page…. 3. 0.400 mol of a gas is heated at constant pressure, so that its temperature increases from 21.00ºC to 79.83ºC. As a result, the gas expands from 10.0 L to 12.0 L against an external pressure of 0.965 atm. The heat capacity of the gas, at constant pressure, is 20.8 J/mol·K. What is the total energy change, U (in J) , for the gas? A) +294 2 mks B) +429 C) +488 D) +685 1 mk E) –294 0.5 mk 4. The threshold frequency for the photoelectric effect with a particular metal is 3.00 ×10 14 Hz. What is the minimum photon energy (in J) needed to eject from this metal one electron with a kinetic energy of 1.00 ×10 19 J? (1 Hz = 1 cycle/second = 1 s ¹) A) 6.62 ×10 19 B) 0.99 ×10 19 0.5 mk C) 2.99 ×10 19 2 mks D) 1.99 ×10 19 0.5 mk E) 3.31 ×10 19 5. Which one of the following statements is false ? A) 2 NO 2 (g) N 2 O 4 (g) is endothermic. 2 mks B) The dissolution of a salt in water can be endothermic or exothermic. C) All specific heat capacities are > 0. D) CO 2 (s) CO 2 (g) is endothermic. E) CO 2 (s) CO 2 (g) does work on the surroundings.
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Name: ____________________________ Student Number: _______________ Version 1 Page 3 continued on next page…. 6. Which of the following redox reactions (as written below) involve the transfer of eight electrons? (i) TiCl 4 (l) + 2 Mg(l) Ti(s) + 2 MgCl 2 (l) (ii) NaH(s) + H 2 O(l) NaOH(aq) + H 2 (g) (iii) 4 KO 2 (s) + 2 CO 2 (g) 2 K 2 CO 3 (s) + 3 O 2 (g) (iv) CH 4 (g) + 2 O 2 (g) CO 2 (g) + 2 H 2 O(g) (v) 9 NaN 3 (s) 3 Na 3 N(s) + 12 N 2 (g) A) iv and v 2 mks B) i and iv 0.5 mk C) iii D) i and ii E) iv 1 mk 7. The enthalpies of fusion and sublimation of sodium metal at the triple point (T and P
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This note was uploaded on 12/12/2011 for the course CHEMISTRY 1E03 taught by Professor Britz during the Spring '09 term at McMaster University.

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Final-exam-2009-solutions - Name: _ Student Number: _...

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