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Department of ChemistryMemorial University of NewfoundlandChemistry 1050FINAL EXAMINATIONFall 2018TIME: 3 hoursREAD THE FOLLOWING CAREFULLY1.This examination consists of 14 pages including a Data Sheet. Ensure that this examination paper iscomplete, i.e. that all 14 pages are present.2.A Data Sheet with a periodic table, equations and physical constants is provided. These are on thelast sheet of the exam and may be detached for use during the examination.3.DO NOT REMOVE ANY PART OF THIS EXAM FROM THE EXAM ROOM4.Answer each question in the space provided. Should you require more space, use the back of theprevious page and indicate clearly where this has been done.5.Show all relevant calculations and justify all simplifying assumptions.6.Numerical answers must be reported to the appropriate number of significant digits with thecorrect units (if any).Do not write in the table below.Good l MarksMark/108

1.In alcohol fermentation, yeast converts glucose to ethanol and carbon dioxide:C6H12O6 (s) 2 C2H5OH (l) 2 CO2 (g)If 5.97 g of glucose reacts, and 1.44 L of CO2 gas is collected at 293 K and 0.997 bar, then what isthe percent yield of the reaction? [4 marks]MM (C6H12O6) 180.1572 g mol–1MM (CO2) 44.0098 g mol–12.Diagram I in each example depicts gas, in a cylinder of variable volume, under particular conditions.[2 marks](a)Circle the diagram, II through IV, that correctly depicts the same amount of gas at the sametemperature but double the pressure compared to that in diagram I.I(b)IIIIIIVCircle the diagram, II through IV, that correctly depicts the same amount of gas at twice thepressure and twice the absolute temperature (in K) compared to that in diagram I.IIIIIIIVPage 2 of 13

3.Three 5 L flasks are each filled with 4.0 g of gas at 298 K. Flask A is filled with H2 (2.0159 g/mol),Flask B is filled with CH4 (16.0426 g/mol) and Flask C is filled with CS2 (76.1407 g/mol).(a)i) With reference to the information given for Flasks A, B, and C, identify the gas havingthe particles with the greatest root mean square velocity. [1 mark]ii) Calculate the root mean square velocity for CH4, methane (in m/s). [3 marks](b)In one hour, 0.315 mol of CH4 effuses through a tiny hole. How many moles of CS2 willeffuse through the same hole in the same amount of time? [2 marks](c)(i)Assume the above gases are now placed in individual containers at STP. Rank therelative densities of the individual gases from smallest to largest. (No calculations arerequired). [1 mark] Smallest(ii) LargestExplain your reasoning for the ranking of the gases. [1 mark]Page 3 of 13

4.A compound has an empirical formula of SF4. At 20.0 oC, 0.100 g of the gaseous compoundoccupies a volume of 22.1 mL and exerts a pressure of 1.02 atm. What is the molecular formula ofthe gas? [3 marks]5.Automobile air bags produce nitrogen gas from the reaction:Molar Masses (g/mol):2 NaN3 (s)65.02 2 Na (s) 3 N2 (g)22.9928.02(a)If 125 g NaN3 reacts to fill an air bag, how much P-V work (in kJ) will the N2 do against anexternal pressure of 101 kPa at 293 K?[3 marks](b)If the process releases 2.34 kJ of heat at constant pressure, then what is the change in internalenergy, U, for the system?[1 mark](c)What does the sign in Part b of this question indicate with respect to the relative energy flowbetween the system and its surroundings? [1 mark]Page 4 of 13

6.Consider the following information.1)2) fHo (H2O (l)) –285.8 kJ/mol fHo (CO2 (g)) –393.5 kJ/mol3)2 C6H14 (l) 19 O2 (g)12 CO2 (g) 14 H2O (l) rHo –8326 kJ/mol(a)Write the reaction equation for the standard molar enthalpy of formation for hexane,C6H14 (l), at 25oC. [1 mark](b)Using the information given above, calculate the standard heat of formation of C6H14 (l) at25oC. [3 marks](c)Calculate the heat of reaction under constant pressure (ie. heat released) when 32.61 g ofC6H14 (l) (86.1766 g/mol) reacts according to the following reaction. [1 mark]2 C6H14 (l) 19 O2 (g)7. 12 CO2 (g) 14 H2O (l) rHo –8326 kJ/mol(a)Distinguish between specific heat capacity and heat capacity. [1 mark](b)In comparing specific heat capactiy and heat capacity, which is the extensive property andwhich is the intensive property. [1 mark](c)A 27.7 g sample of the radiator coolant ethylene glycol releases 688 J of heat. What is theintial temperature of the sample if the final temperature is 32.5 oC? (Specific heat capacityof ethylene glycol is 2.42 J/g oC). [2 marks]Page 5 of 13

8.Isooctane is a component of gasoline and is used as a reference standard in determining the “octanerating” of a fuel mixture. Suppose 0.6950 g isooctane, C8H18 (MM 114.2302 g/mol), undergoescombustion in a bomb calorimeter and a temperature change from 25.000 oC to 28.310 oC isobserved. The heat capacity of the bomb calorimeter is 9.980 kJ oC–1.(a)Write a balanced chemical equation for the combustion of one mole of isooctane, C8H18 (l),at 298.15 K. [1 mark](b)Determine rU for the combustion of isooctane at 298.15 K. [3 marks](c)Determine rH for the combustion of isooctane at 298.15 K. [1 mark] 9.(a)What is the Aufbau principle? [0.5 marks](b)Below is a plot of the total radial probability diagram for the 1s, 2s and 2p orbitals.On the plot, identify the curve that best represents the total radial probabilities for the 1s, 2sand 2p orbitals. [1.5 marks](c)Briefly explain why the 2s orbital is generally lower in energy than the 2p orbital. [1 mark]Page 6 of 13

10.(a)What is the energy (in kJ/mol) associated with light of wavelength of 330 nm? [2 marks](b)(i) How many 4p orbitals are there in an atom? Explain, in terms of quantum numbers, howyou came to your answer. [2 marks](ii)What is the maximum number of electrons possible in the 4p orbitals of an atom?[1 mark](c)Write a full electron configuration for a sodium atom. [1 mark](d)Write the set of four quantum numbers that describe the valence electron(s) in sodium.[1 mark](e)Is sodium diamagnetic or paramagnetic? [1 mark](f)Write a full electron configuration for the 1 cation of sodium. [1 mark](g)How would you expect the size of the sodium atom to compare to its 1 ion? Briefly explainyour answer. [2 marks]Page 7 of 13

11.12.The following questions are related to the expected electron configurations in multielectron atomsand ions.(a)Identify the atom with the condensed ground state electron configuration of[Xe]4f145d106s26p3. [1 mark](b)Write the condensed ground state electron configuration for zirconium, Zr. [1 mark](c)Write a condensed ground state electron configuration and condensed orbital box diagramfor cobalt, Co. [1 mark](d)Write the charge and condensed ground state electron configuration for the most stablemonoatomic ion formed by selium, Se. [1 mark](e)Using condensed ground-state electron orbital box diagrams, explain briefly why the twomost common ions of tin are Sn2 and Sn4 . [2 marks]Consider the following and provide the requested information. [1 mark each](a)Order the following elements according to increasing Zeff: Ca, Se, Kr, K Lowest(b)Circle the element with the lowest electronegativity.Pb(c)SnSiWSFrNeZnArrange the following in order of increasing first ionization energy: F, K, P, Ca, Ne. Lowest(e)CCircle the element with the largest atomic radius.Au(d) Highest HighestIdentify the Period 3 element with the following successive ionization energies, IE.(in kJ/mol).IE1 1012, IE2 1903, IE3 2910, IE4 4956, IE5 6278, IE6 22,230Page 8 of 13

13.14.Write the balanced equations for the following. [1 mark each](a)Write a balanced chemical equation to demonstrate the reaction between solid calcium andbromine gas.(b)Write a balanced chemical equation to demonstrate the reaction between solid magnesiumand liquid water.(c)Write a balanced chemical equation to demonstrate the reaction between solid iodine andhydrogen gas.Below is the skeletal structure for n-propargylacrylamide, C6H7NO. Complete the Lewis structurefor n-propargylacrylamide by placing lone pairs and multiple bonds where required. Two skeletalstructures are given (use one for practice, if necessary), circle the one you want graded. [2 marks]H CHHCNH15.CO HHCCCHH CHHHCNCO HHCCCHComplete the following table to provide the missing data. For Lewis structures, the final structuresshould consider minimizing formal charge.Sulfur dibromide, SBr2Xenon tetraflouride, XeF4Lewis Structure(1 mark each)Sketch of VSEPRpredicted shapeincluding bondangles(1 mark each)Name themolecular shape.(1 mark each)Is it polar ornonpolar?(0.5 mark each)Page 9 of 13

16.Epinephrine (or adrenaline) is a naturally occurring hormone that is also manufactured commerciallyfor use as a heart stimulant, a nasal decongestant, and a glaucoma treatment.(a)For the N atom in epinephrine, what is its shape and hybridization? [1 mark]Shape:(b)For the ring C atoms, what is their shape and hybridization? [1 mark]Shape:(c)17.Hydridization:Hydridization:How many electrons are delocalized in the ring? [1 mark]Consider the following resonance structures for COF2.FOOCCFStructure AFFStructure B(a)Assign formal charges to the atoms in the structures above by placing all nonzero formalcharges next to the atom in the respective structures. [1 mark](b)Identify the major contributor to the resonance hybrid and explain your reasoning. [1 mark](c)For Structure A above, use valence bond and orbital hybridization theories to describe thebonding in this molecule. In doing so, you are required to provide a sketch illustrating andlabelling the types of all the bonds in the molecule, sigma ( ) or pi ( ) bonds, and the atomicand/or hybrid orbitals that overlap to form these bonds. [4 marks]Page 10 of 13

18.19.Answer the following questions:(a)Explain the main difference between molecular orbital theory and valence bond theory.[1 mark](b)What is an antibonding orbital? [1 mark](c)Sketch and correctly label any 3d orbital. In your drawing include orbital phases ( or –)and appropriately label xyz axes. [1 mark](d)Below are two 2px orbitals. Sketch and label the phases ( and -) of the antibonding *2pmolecular orbital they would generate. [1 mark]Using molecular orbital theory, provide the following:(a)Draw molecular orbital energy level diagrams for the following two species: He2 and HHe.(Treat HHe as a diatomic molecule with three electrons.) In your diagrams, remember tolabel all atomic and molecular orbitals and place the correct number of electrons in the MOs.[2 marks each]Molecular Orbital Diagram for He2(b)Molecular Orbital Diagram for HHeDetermine the bond order for each of He2 and HHe. [1 mark each]Bond order for He2Bond order for HHePage 11 of 13

20.Answer the following questions with respect to intermolecular forces.(a)Of the substances, ethane (C2H6) or octane (C8H18), circle the one you expect to have thelarger dispersion forces. [1 mark]H HH CCH H H H H H H HHH CH HCCCCCHH H H H H H H HStructure of ethane, C2H6(b)C CStructure of octane, C8H18Diethyl ether has a boiling point of 34.5 oC and 1-butanol has a boiling point of 117 oC withthe structures of each of these compounds shown below.H HH H H HH HH C C O C CH HH C CHC C OHH H H HH HDiethyl ether1-butanolBoth of these compounds have the same numbers and types of atoms. Explain the role thatintermolecular forces play in determining boiling points of compounds and, in so doing,explain the difference in the boiling points of diethyl ether and 1-butanol. [2 marks](c)The Lewis structures for SO2 and CO2 are shown below. Circle the compound you expect tohave the higher boiling point. [1 mark](d)Using the letter designations assigned in each structure, rank the following compounds inorder of increasing vapor pressure at 298 K. [1 mark]CH3–O–CH3ACH3–CH2–OHB Lowest(e) HighestCircle the member of the following pair of substances that you expect would have the higherboiling point. [1 mark]orF2(f)CH3–CH2–CH3CLiFCircle the species that are capable of hydrogen bonding among themselves. [1 mark]BeH2HINH3CH4Page 12 of 13

21.The vapour pressure of benzene, C6H6, is 0.053 bar at 281 K. What is its vapor pressure at 334 K?The molar heat of vaporization of benzene is 31.0 kJ/mol. [3 marks]22.Consider the following phase diagram for hexane below.(a)On the phase diagram above, label the following: [0.5 mark each](i)(ii)(iii)(iv)(v)(vi)SolidLiquidGasTriple pointCritical PointSupercritical fluid(b)What does the term “triple point” mean with respect to a phase diagram? [1 mark](c)Using the diagram above, determine the normal boiling point (in oC) of hexane.[1 mark](d)Determine the phase change that takes place as the pressure of hexane is reduced from1.0 bar to 0.5 bar at 40 oC. [1 mark]The EndPage 13 of 13

Constants fus H Ho 2O(s ) 6.01 kJ mol 1 at 273 Kc 2.998 108 m s 1 vap H Ho 2O(l ) 40.7 kJ mol 1 at 373 KRH 1.0973 107 m 1h 6.626 10 34 J s vap H Ho 2O(l ) 44.0 kJ mol 1 at 298 Kspecific heat of H 2 O(l ) 4.184 J g 1KN A 6.022 1023 mol 1 1specific heat of H 2 O(s ) 1.960 J g 1 K 1 at 0 o Cdensity of H 2 O(l ) near 0 o C 1.000 g mL 1En (J) 2.179 10 18 n2 a P 2 V nb nRTV Z2n21 mL 1 cm31 J 1 kg m 2 s 2 11 T1 T21 bar 105 Pa 100 kPa 750.1 torr 0.9869 atmEk 1 2mv2 r H rU nRTrn n 2 aoZ2 curms 1 bar L 100 J1 atm L 101.325 J1 L 1 dm3oo r H o p f H products r f H reactantsEn h F 9.6485 104 C mol 11 cal 4.184 J (exactly) U q w 11 E (J) Z 2 2.179 10 18 2 2 ni nf P vap Hln 2 R P1 0.08314 L bar mol 1 K 1Conversion FactorsSome Useful EquationsPV nRTR 8.314 J mol 1 K 13RTMrate A rate BhmvMBMA

(c) Write a condensed ground state electron configuration and condensed orbital box diagram for cobalt, Co. [1 mark] (d) Write the charge and condensed ground state electron configuration for the most stable monoatomic ion formed by selium, Se. [1 mark] (e) Using condensed ground-state electron orbital box diagrams, explain briefly why the two

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