Midterm One Answers - 1 0 CH3 Test Form A H3C CH3 H3C c H3...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 4
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 6
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1) 0 CH3 . Test Form A H3C CH3 H3C c H3 Acetone 2—methyl propane Acetone boils at a significantly higher temperature than 2-methy1 propane, A) because the density of acetone is greater than that of 2—methy1propane B) because the attractive dispersion forces in 2-methylpropane are weaker than those in acetone C) because the molecular mass of acetone is slightly less than that of 2-methyl propane D_) because dipole—dipole forces are always greater than dispersion forces @ecause the attractive dispersion forces in 2-methylpropane are weaker than the dipole forces in acetone 2) In which of the following pure substances will hydrogen bonding be an important intermolecular force? H CHsCHon \ H3C““ \ 1 2 3 4 A) All B) 3 and 4 C l and 2 C152 and 3 E) none 3) List the following three compounds in order of increasing boiling point: CH3 1 2 3 A) 1,2,3 B) 1,3,2 c . 2,1,3 D)-2,3,1 E) 3,2,1 4) What is the dominant intermolecular force for pure acetylacetone. M E A) Hydrogen bonding 0* O @dipole—dipole 33:13:1er Mm A it Ms- E) none of these A soluble in both water and hexane B) soluble in water and insoluble in hexane C) soluble in hexane and insoluble in water D) insoluble in both water and hexane (5:)?Acetylacetone would be expected to be 6) The melting points ofthe following compounds are as follows: N32B4O7(HZO)]0 mp 7430C, B8203 mp 0C, BF3 mp -1270C What is the best explanation for this range in melting points? ® They form an ionic solid, network solid and a molecular solid respectively B) They form an ionic solid, molecular solid and a network solid respectively C) They form a molecular solid, network solid and ionic solid respectively D) The first can do hydrogen bonding, the other two only have dipole-dipole forces E) The larger the molecular weight the stronger the intermolecular forces. _CQ_2 Phase Diagram Supercnfical fluid Solid Pressure (atm) #4TWwWM : ~78i5 M ii i i i i U ‘3‘].1 'l'cmpcm rurc (“C) ——> 7) A sample of C02 is warmed at a constant pressure of 1 atm from —90°C to 32°C. The sample will A) Melt from solid to gas B) Sublime from solid to gas to super critical fluid C Sublime from solid to gas D) Melt from solid to liquid E) Deposit from gas to solid 8) A sample of C02 is held at a constant temperature of -56.2°C. The pressure is lowered from 100 atm to 3 atm. The sample will be observed to go from A) Gas to liquid to solid B) Solid to liquid C) Liquid to solid D Liquid to gas Solid to liquid to gas 9) What is name of the point at 5.11 atm and -56.4°C? A Normal melting point B riple point Critical point D) Normal boiling point E) Franklin H. Smith 10) What is the normal boiling point of C02? A) 311°C B) -56.4 °C C) —78.5 0C 511°C E 02 doesn’t have a normal boiling point. The crystal structure of Zinc Sulfide is shown above. The Sulfurs are the light spheres and the Zincs are dark spheres. A' nS 11454 C) zmsm D) 211287 E) ZII4$7 @ZWhat is the chemical formula of zinc sulfide? Z 12) What is the best way to describe the positions of the sulfurs? A) In tetrahedral holes surrounded by zinc atoms B) simple cubic C) body centred cubic heXagonally close packed E) ace centred cubic 1) What is the best way to describe the positions of the zincs? n tetrahedral holes surrounded by sulfur atoms B) simple cubic C) body centred cubic D) hexagonally close packed D) face centred cubic l4) Polonium metal is one of the few known cases of metals adopting a simple cubic crystal structure. Why is this structure so uncommon for metals? A) Simple cubic has a high packing efficiency Simple cubic has a low packing efficiency C) Simple cubic occurs if the element is radioactive and there are few radioactive elements D) The holes will become filled with cations , E) The holes will become filled with anions CL_:.Zr“ 16) Before it was banned, the concentration of the insecticide Dichlorodiphenlytrichloroethane (DDT) (mw = 354.49 g/mol) was found in a lake to be 2.0 x 10‘6 ppm. How many grams of DDT were in 15 kg of lake water? A)3.0x10‘2g 2 01 low m W C, 22232:: ’ i at 0' 0' . x D)1.3x10'9g 3 E)1.3x10""g , A, . , ~ 0 O LUXW f K lSkfijnio x woof) —;, 3,0X\O'”%L3 Cl ' c: ‘43 “ “ ll) 3“le Kg. 17) Despite the low concentration in lake water, fish from the lake had 1 1 ppm of DDT in their flesh. A chemist explains this happens because: “A DDT forms strong hydrogen bonds with water " DDT get stored readily by fat C) DDT dissolves readily in urine D) DDT has dipole—dipole interactions with fat E) DDT has greater dispersion forces than fat because of the chlorines. l8) Calculate the vapour pressure of water above a 1.07 M solution of urea (NH3)2CO (mw 60.06, xurea = 0.019). The vapour pressure of pure water at this temperature is 4.40 kPa. ‘ I A) 4.316 kPa V toO‘jrmofl 4 Eli.) Co” B) 4.48 kPa x/O DC V?ka _ f L L 2? A .2 t t LB 0 C) 8.36 x10 kPa @3823: V3,» oi Pm {WO’QA 2 19) A can of soda pop at 25°C is under 2.45 atm of C02 pressure. What is the concentration of C02 in the soda? A) 2.6 x 10'3 M B)0.19M [Col] : K”<Pcot7 63.9x10‘3M D 8.3 10‘2M 4). E)0.19)lM ~= 3.‘lfl0 "WC Lil-K MW 20) List the following aqueous solutions in order of increasing boiling point 1) 0.30 M NaC12) 0.75 M CH3CH20H 3) 0.25 M MgClz, 4) 0.50 M glucose. 3:331:11? L j -c L 1xL‘ons. @«LH 0 NLCQ 030M 0on E) none ofthe above 7:) Etch) O H O: H l ‘ 37H§d1 o.2§m 035% L032?“ osofi OSOH 21) At 25°C , the equilibrium pressure of HCl vapour above a 1.00 M aqueous solution ofHCl is 0.00523 atm. Ifthe concentration of HCl is increased 7 times, what is the vapour pressure? @00366 atm B) 1.91x102atm [ HCQ] = KH C) 0.191 atm D) 0.000747 atm ' 0L P ' E) 191 atm o L 3X} 03 F X :l' (3.063‘2’gafi'm Kil‘ ’2. % - (9C: KtD—Zoxwxl 22) What is the freezing point ofa mixture of45 g glucose (C6H206, mw = 180.1g/mol) and 145 g H20. 23-09;? An = Kt b We 33—32855 :1.%S%°cx5.l.’+z‘$miQ b: 45- x 3;» XL“; 3292: @—3.2oc "we K3 13043 p.539t :: 32. /* ‘ . : 1.123% I) : 170.5be = O C‘3'.2’L K5 2 -3 -Z°c 23) Sea water has dissolved ions and molecules having a total concentration of 1.05 mol/L. What is the osmotic pressure of sea water at 20°C? A) 2.54 atm 1T: M RT = 133539. 0. O 1679?? L». “W . (20 +2?3.\g‘\c) 25.4 atm . L Mbl \C C)25.7 t __ D) 1.7 aztlmm " 25' 3 24) The figure below represents a monolayer of the surfactant sodium stearate on a liquid surface. \\_,./\K,f\vf\/rsv,r‘xx'./u\/J‘\/\fl NI) 3.} Rumba”) E) The solvent is Swim gag-3.53; Sit’l‘t'g‘vfazit'fl tli‘y‘]; {inn ‘ ul 21:0; vacuity; .izlisui A pOIar non—polar = :4“ r " ' ‘~ c ) hydrophillic D) B and C E) A and C 25) 10g of NaOH was dissolved in 20 mL of water. The flask got dangerously hot. Select the true statement: A) AHSO1n for NaOH is negative B) more NaOH can dissolve in warm water than in cold C) solvating Na+ and OH' with water molecules is more energetically favourable than maintaining the coulombic attractions between Na+ and OH" in the solid D) dissolving NaOH is an exothermic process @ all are true 26) Without doing any calculations what is the sign of AS for this reaction NaOHm H Na+<aq> + OHkaq) @+ B)- C) 0 D) depends on temperature E) depends on concentration 27) Without doing any calculations What is the sign of AS for this reaction 2CH3OH<g>+302(g) —* 2C02(g) + 4H20(g) , Lo M 5 + I? ~ Ll M 5“- C) 0 D) depends on temperature E) depends on vapour pressure 28) Without doing any calculations what is the sign of AS for this phase change CH4(1) —’ CH4(s) @Jr ) 0 D) depends on temperature E) depends on pressure 29) Find the false statement A11 spontaneous chemical reactions have a positive AS B) Entropy is the dispersal of matter and energy C) All spontaneous chemical reactions have a negative AG D) A non—spontaneous reaction is spontaneous in the reverse direction. B) All are true 30) Diethyl ether ( CH3CH20CH2CH3, bp = 34.6, AHf = +27.247 kJ/mol) in a small puddle (10.0 g, 0.134 mol) boils in a room sitting at 45.0 0C. The heat (q) transferred from the surroundings to the room as the diethyl ether vaporizes is 3.64 kJ. What is the change in entropy of the diethyl ether puddle as evaporates? A) 11.5 kJ/K B) 0.0118J/K AS = -,— 3M : 0.01% K) C) 11.5 J/K - I? L3H” +733J§K3 AC gas/K .. Uta/K 8 31) As the diethyl ether evaporates A) the entropy of the ether decreases ' heat is transferred from the diethyl ether to the room ‘ @me entropy change of the surroundings will be negative ) the heat is transformed into work E) the entropy of the universe decreases 32) 3.— Clzrgi + H2(g) —’ ZHC1(g) 0 “Amp 223 -\ 13mg my a V Using the information given in the table on page 2, what is the standard entropy change of this unbalanced reaction? ‘. _ . , -18.46 J/mol AS : pm ml; ' (“st .3 20.0 J/mol K \ C)—109.0J/molK :' 1039,60 ’CusA -\- 80198 D) 373 J/K E de e d thetem tue —; _o ) p n s on pera r 2 o J/MO‘ K, 33) Knowing that for the reaction in Q 32 the AH"rxn is -184.6 kJ/mol, the reaction is spontaneous at all temperatures 3 spontaneous only at low temperatures : " «(0 Q "‘ T (20' 0-: C) spontaneous only at high temperatures D) never spontaneous E) do not have enough information 34) Solid Phosphorus has two forms named for their appearance: red and white. Using the table on page 2, which phase has the more ordered structure? A) white phosphorus is more ordered @red phosphorus is more ordered ....:) [W W0 ? C) they are the same :3 D) cannot tell from information given E) pink phosphorus T P(s,white) —* P(5,Ted) 5° ’1 .8 “i fiolk‘ 2 ° to -- [’H’ g o. . . . . . ASHA$ 12'8 “Lu'q Usmg the informatlon glven 1n the table on page 2, th1s reaction 1s a __ I 8. (a not \L A) spontaneous at all temperatures '- — t ll t tu B) non spontaneous a a empera res ARWA 3 _ __ b C) spontaneous only at high temperatures pontaneous only at low temperatures * ‘- " not enough information given 36) Benzene has a vapour pressure of0. 132 atm at 261°C. At a higher temperature of 400°C, it has a vapour pressure of 0.230 atm. What is AHvap for benzene? ‘ ' 3) 3.12 x104 kJ/mol R : mam ‘\ : 291°C 4. 143 A; = 233.231; ) 30.6 kJ/mol C) 347 J/mol put 01% m Ti, quooC .t 273 .\S’ a 31%. \S‘ \c D) —3~l.2 kJ/mol ‘ , ® 31.2 kJ/mol 37) Repeat your answer for Q 36 (to make the question worth two marks) “6%) = H;— ail Q 38) BONUS What is the best explanation for the colligative property in which boiling point increases with increasing solute concentration. A) The solute decreases the rate of escape of the solvent molecules from the liquid phase. The entropy of the liquid phase is larger, meaning the AS for the phase change is less positive and a higher temperature is required to make the phase change spontaneous. C) The entropy of the liquid phase is larger, meaning the AS for the phase change is less negative and a higher temperature is required to make the phase change spontaneous. D) The AHvap becomes less positive making the AGvap negative only at higher temperatures E) The addition of solute broadens the transitions in the phase diagram. 10 ...
View Full Document

{[ snackBarMessage ]}

Page1 / 8

Midterm One Answers - 1 0 CH3 Test Form A H3C CH3 H3C c H3...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online