Name: Teacher: DO NOT OPEN THE EXAMINATION PAPER UNTIL YOU ARE TOLD BY THE SUPERVISOR TO BEGIN CHEMISTRY FINAL EXAMINATION June 2013

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1 Name: Teacher: DO NOT OPEN TE EXAMINATION PAPER UNTIL YOU ARE TOLD BY TE SUPERVISOR TO BEGIN EMISTRY 0 FINAL EXAMINATION June 013 Value: 80 Marks Duration: ours General Instructions This examination consists of two parts. Both parts are contained in this booklet and further general instructions are provided on appropriate pages. Part I Selected Response (40 marks) Select the letter of the correct response from those provided. EITER shade the letter on your computer scorable card OR place the letter in the blank provided on your Multiple hoice Answer Sheet, whichever format is being used by your school for this exam. Do ALL questions in this section. Part II - onstructed Response (40 marks) Answer ALL questions fully and concisely in the space provided. Show all work and use correct units and significant digits in all final answers. Student hecklist The items below are your responsibility. Please ensure that they are completed. Write your name and teacher's name on the top of this page. Write your name, teacher s name, course name and number on the Part I answer sheet. heck the exam to see that there are no missing pages. ALL MATERIALS MUST BE PASSED IN WIT TIS EXAM. Use your time wisely. Good luck! hemistry 0 Final Exam June 013 Page 1

2 Part I Selected Response Total Value: 40 Marks 1. Which isotope has 9 protons and 10 neutrons? (A) fluorine-10 fluorine-19 neon-10 (D) neon-19. Which is defined as the amount of carbon atoms in a 1g sample of carbon-1? (A) Atomic mass Avogadro s number Limiting reagent (D) Standard pressure 3. What is the number of hydrogen atoms in.3 moles of N 3? (A) x 10 4 (D) 4. x The imaginary element jensenium has two known isotopes, as shown by the data below. What is the average atomic mass of jensenium? Isotope Percentage Abundance (%) Isotopic Atomic Mass (amu) jensenium jensenium (A) 71.9 amu 7.3 amu 73.0 amu (D) 73.7 amu hemistry 0 Final Exam June 013 Page

3 5. What is the molar mass of aso 4 O? (A) g/mol g/mol g/mol (D) g/mol 6. A 30.61g sample of a compound with the chemical formula NalO x contains 0.500mol. What is the identity of the compound? (A) NalO NalO NalO 3 (D) NalO 4 7. What is the number of moles in 4.00 g of magnesium? (A) (D) Which term represents the volume of one mole of gas at STP? (A) molar mass molar volume percent composition (D) percent volume 9. What is the percentage of potassium by mass in K S? (A) 9.08% 35.46% 58.16% (D) 70.9% hemistry 0 Final Exam June 013 Page 3

4 10. A compound has an empirical formula of O and a molar mass of 90.09g/mol. What is the molecular formula of the compound? (A) O 4 O 3 6 O 3 (D) 4 8 O Which has low solubility in water? (A) aso 3 KNO 3 MgS (D) Nal 1. What are the units for molar concentration? (A) g/l L mg (D) mol/l 13. What mass of sodium is contained in a 50 g solution which has 7.0 ppm of sodium? (A) 3.6 x 10-5 g 1.8 x 10-3 g.8 x 10 4 g (D) 1.7 x 10 9 g 14. What is the final concentration when 1.60 L of.5 mol/l l(aq) is diluted to a final volume of 4.80 L? (A) 0.13 mol/l 0.83 mol/l 1. mol/l (D) 7.5 mol/l hemistry 0 Final Exam June 013 Page 4

5 15. The solubility of Nal in water is 359g/L at 5. Which term describes a Nal solution which is 375g/L at 5? (A) concentrated dilute saturated (D) supersaturated 16. Which is a volumetric flask? (A) (D) hemistry 0 Final Exam June 013 Page 5

6 17. Which term represents the amount of product obtained from a chemical reaction? (A) actual yield excess reagent limiting reagent (D) theoretical yield 18. For the reaction: 3 8 (g) + 5 O (g) 3 O (g) + 4 O(g) ow many moles of carbon dioxide are produced when 4. mol of oxygen reacts with sufficient propane? (A) (D) Which is a metallic solid at room temperature? (A) S uzn Lil (D) SiO 0. ow many valence electrons are in an atom of nitrogen, N? (A) 3 5 (D) 7 1. Which has a triple bond? (A) Br N (D) O hemistry 0 Final Exam June 013 Page 6

7 . Which Lewis diagram is correct? (A) P P P P P P (D) P P 3. What is the shape around a central atom with bonding groups and lone pairs? (A) bent (v-shaped) pyramidal tetrahedral (D) trigonal planar 4. Which shape repeats in the macromolecule of Buckminsterfullerene? (A) (D) bent (v-shaped) pyramidal tetrahedral trigonal planar hemistry 0 Final Exam June 013 Page 7

8 5. Which contains London dispersion and dipole-dipole forces only? (A) O O (D) N 3 6. Which is ranked from lowest to highest bond polarity? (A) F l Br F Br l Br l F (D) F l Br 7. Which compound contains network covalent bonding? (A) l 4 sbr O (D) Si 8. Which represents the bonding between aluminum, Al, atoms and bromine, Br, atoms? (A) Al + 3 Br Br - Al Br 3+ - Br - 3+ Al + Br Al Br - Al + 3 Br Br Al Br Br (D) Al + Br Al Br 9. What explains the malleability of copper, u(s)? (A) cations attracted to anions cations surrounded by a sea of electrons network of covalent bonds (D) sharing of electrons between atoms hemistry 0 Final Exam June 013 Page 8

9 30. Which compound would have the highest boiling point? (A) cis-dichloroethene ethene ethyne (D) trans-dichloroethene 31. The synthesis of which compound led to the modern definition of organic chemistry? (A) benzene DNA polyester (D) urea 3. Which is an aliphatic hydrocarbon? (A) alkene amine ether (D) ketone 33. Which is an alkane? (A) (D) What is the name of the compound below? (A) (D),6-diethylheptane -ethyl-3-methyloctane -ethyl-6-methyloctane 3,7-dimethylnonnane hemistry 0 Final Exam June 013 Page 9

10 35. Which is a structural isomer of this molecule? (A) (D) 36. Which reaction represents thermal cracking? (A) (D) heat (l) 9 0 (l) 8 16 (l) catalyst (l) 9 0 (l) 8 16 (l) catalyst 9 0 (l) 8 16 (l) (l) heat 9 0 (l) 8 16 (l) (l) 37. Which contains a carboxyl functional group? (A) propanoic acid propanol propanone (D) propylamine 38. What possible product(s) form from the reaction of -pentene with hydrogen bromide, Br? (A),3-dibromopentane -bromopentane and 3-bromopentane -methyl--bromobutane (D) ethane and 1-bromopropane hemistry 0 Final Exam June 013 Page 10

11 39. Which structure has delocalized electrons? (A) (D) 40. Which is a product of esterification? (A) 3 O O 3 O O 3 3 O (D) 3 O 3 End of Part I hemistry 0 Final Exam June 013 Page 11

12 Part II onstructed Response Total Value: 40 Marks Answer ALL questions in the space provided. Show all workings and report all final answers with correct significant digits and units. Value 41.(a) alculate the mass of 9.75L of neon, Ne(g), at STP. Answer: n Ne V 9.75L 0.435mol.4 L / mol.4 L / mol 1 point So: m n M 0.435mol 0.18 g / mol Ne Ne mne g 1 point (b) alculate the percent composition of a pure substance that contains 6.01g of copper, 3.0g of sulfur and 5.97g of oxygen. Answer: totalmass 6.01g 3.0g 5.97 g g 6.01gu % u x % u 15.00gtotal 3.0gS % S x % S 15.00gtotal % O100% (40.1% 0.1%) 39.8% O hemistry 0 Final Exam June 013 Page 1

13 Value 41. (continued) 3 (c) alculate the empirical formula of a compound with the percent composition of 88.80% and 11.0%. Answer: Assuming a 100g sample, Percent to mass: m = 88.80g ; m = 11.0g ; Mass to moles: m 88.80g n mol M 1.01 g / mol n m 11.0g mol M 1.01 g / mol 1 point Divide by lowest: 1 point Multiply until whole. In this case, we need to multiply by. x The empirical formula is 3 (d) alculate the mass of lithium sulfide, Li S, required to prepare ml of 0.50 mol/l Li S(aq) solution. Answer: Switch volume to litres: 500.0mL = L alculate moles: n V (0.50 mol / L)( L) 0.15mol LiS Aside: Get molar mass of Li S: x Li = x 6.94 g/mol = 13.88g/mol 1 x S = 1 x 3.07g/mol = 3.07g/mol = 45.95g/mol Li S alculate mass: m nm (0.15 mol)(45.95 g / mol) 5.74g Li S hemistry 0 Final Exam June 013 Page 13

14 Value 41. (continued) (e) A solution of Nil (aq) has a chloride ion concentration of 0.378mol/L. What is the Nil (aq) concentration? (Include a balanced chemical equation with your response.) Answer: Dissociation: Nil (aq) Ni + (aq) + l - (aq) s Given: V = L Want: =? Nil Given: = 0.378mol/L Mole ratio, using concentrations: moll l Nil 1mol Nil 1 point mol l L (1 molnil ) moll Nil mol / L Nil Nil 3 (f) Sodium metal, Na(s), reacts with an unknown gas, X (g), according to the balanced reaction below: Na(s) + X (g) NaX(s) When 1.00g of the gas reacts, 13.6g of sodium metal is required for a complete reaction. What is the identity of the gas? Answer: Get moles: mna 13.6gNa nna mol Na M.99 g / molna Na 1 point Mole Ratio: 1 molx nx ( molna) mol X mol Na 1 point onvert to Molar Mass: M X mx 1.00gX g X n 0.96mol X mol X g Note: Since this is diatomic, M X mol g / mol X This molar mass matches chlorine, l. The gas is l (g) hemistry 0 Final Exam June 013 Page 14

15 Value 41. (continued) 4 (g) For the reaction: ao(s) + F(aq) af (aq) + O(l) 1.5g of calcium oxide, ao(s), is reacted with 0.475L of 0.800mol/L hydrofluoric acid, F(aq). Determine the limiting reagent. (i) (ii) Determine the limiting reagent. alculate the concentration of af (aq) produced. Answer: Limiting reagent problem. Get moles for each reagent, and do a mole ratio for each reagent. Get moles, ao: mao 1.5gaO nao molao M g / molao ao Aside: 1 x a = 1 x 40.08g/mol = 40.08g/mol 1 x O = 1 x 16.00g/mol = 16.00g/mol = 56.08g/mol 4 Mole Ratio of product af, based upon ao: 1 molaf naf (0.3 molao) mol af from ao) molao Get moles, F: n V (0.800 mol / L) (0.475 mol) molf F F Mole Ratio of product af, based upon ao: 1 molaf naf (0.380 molf ) mol af fromf ) mol ao ompare the results from each mole ratio; conclude that the theoretical yield is 0.190mol of af. This means that the limiting reagent is F. (ii) alculate the concentration of af(aq) that would be produced. n mol mol L af V L Science communication: For any two of: significant figures, units, or use of formulas. () () hemistry 0 Final Exam June 013 Page 15

16 3 4.(a) omplete the following table for methanol 3 O. Lewis Diagram O (1 mark) VSEPR Shape diagram O (1 mark) Name of shape around each central atom Tetrahedral (0.5 mark) Bent (0.5 mark) (b) i) Water, O (l) is poured into a test tube containing carbon tetrachloride, l 4 (l). The test tube is shaken and then allowed to settle. The test tube is shown below. Explain why the layers form. Answer l 4 is nonpolar (0.5 mark) O is polar (0.5 mark) like dissolves like therefore polar substances are immiscible in nonpolar substances (1 mark) hemistry 0 Final Exam June 013 Page 16

17 Value 4. (continued) (b) ii) To determine which layer is water and which layer is l 4 (l), a hemist adds purple iodine crystals, I (s) to the same test tube. The test tube is shaken and allowed to settle for a second time. Based on the results you see below, how can you be certain the fluid in the bottom layer is l 4 (l)? Explain. Answer Upper layer is water (0.5 mark). I is nonpolar substance (0.5 mark) therefore will be miscible in nonpolar solvent (l 4 ) (1 mark). (c) Explain why a molecule of l is polar. Justify your answer with a diagram. Answer EN =.1 l EN = 3.0 (1 mark) In the l molecule a bond dipole exists between the and the l as a result of the difference in electronegativity between the and l. The shared pair of electrons is partially pulled toward the more electronegative l resulting in a charge separation between the and l. The overall effect is a polar bond toward the l. hemistry 0 Final Exam June 013 Page 17

18 Value 4. (continued) 3 (d) Rank the following substances in order of increasing boiling points. Justify your answer. potassium chloride, Kl fluoroethene, 3 F ethene, 4 Answer: We first realize that Kl is ionic; fluoroethene and ethane are molecular. This immediately places Kl at the higher boiling point. The relative ranking of the fluoroethene and ethane then comes down to the relative sizes of their intermolecular forces: 6 (0.5 mark) 5 F (0.5 mark) Kl (0.5 mark) Low LD (16e - ); no DD igher LD (4e - ), has DD ionic (0.5 mark) (0.5 mark) (0.5 mark) 3 43.(a) omplete the table with either a structural diagram or IUPA name. IUPA Name Structural Diagram 1,3-dichloro benzene l l O -heptanone ,5-dimethyl--hexyne hemistry 0 Final Exam June 013 Page 18

19 Value 43. (continued) 4 (b) Draw and name two isomers for 6 O. Structure 1: Structure : O 3 3 O 3 (1 mark) (1 mark) Name: ethanol (1 mark) Name: dimethyl ether or methoxy methane (1 mark) c) From the reactions given, draw the structures for compounds A, B and. Step1: 3 O 3 acid 3 ompound A + O Step : ompound A ompound B Step3: Br + UV light Br ompound B ompound + Br Note: It is possible that there are two possible answers for ompound Two possible isomers for ompound : 3 Br 3 Br 3 hemistry 0 Final Exam June 013 Page 19