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PracticeExam3

# PracticeExam3 - Practice Exam 3 CHM 114-A Prof A Angel...

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Unformatted text preview: Practice Exam 3 CHM 114-A Prof. A. Angel] Spring 2004 Name Section MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A gas vessel is attached to an open—end manometer containing a nonvolatile liquid of density 0.791 gme as shown below. The difference in heights of the liquid in the two sides of the manometer is 43.4 cm when the atmospheric pressure is 755 mmHg. Given that the density of mercury is 13.6 glmL, the pressure of the enclosed gas is atm. A) 0.990 B) 0.98? C) 0.993 D) 0.960 E) 1.03 2) "Isothermal" means A) at Constant pressure C) at ideal temperature and pressure conditions D) at constant temperature E) at variable temperature and pressure conditions 3) A sample of gas (24.2 g) initially at 4.00 atm was compressed from 8.00 L to 2.00 L at constant temperature. After the compression, the gas pressure was atm. A) 16.0 B) 2.00 C) 8.00 D) 4.00 E) 1.00 4) A gas is considered "ideal" if A) its behavior is described by the ideal—gas equation B) it is not compressible C) one mole of it in a one—liter container exerts a pressure of exactly 1 atm at room temperature D) one mole of it occupies exactly 1 liter at standard temperature and pressure E) it can be shown to occupy zero volume at 0°C. 5) The density of ammonia gas in a 4.32 L container at 837 torr and 45°C is gfL. A) 0.432 B) 3.86 C} 4.22 x10‘2 D) 0.717 E) 0.194 6) Automobile air bags use the decomposition of sodium azide as their source of gas for rapid inﬂation: 2NaN3 (s) “1 2Na (s) + 3N2 (g). What mass (g) of NaN3 is required to provide 400 L ong at 25°C and 763 torr? A) 71.1 B) 1.64 C) 107 D) 1.09 E)160 7) The density of air at STP is 1.285 gfL. Which of the following cannot be used to fill a balloon that will float in air at STP? A) NH3 13) NO C) HF D) CH4 E) Ne 8) A gas mixture of Ne and Ar has a total pressure of 4.00 atm and contains 16.0 mol of gas. If the partial pressurL of Ne is 2.75 atm, how many moles of Ar are in the mixture? A) 6.75 B) 12.0 C) 5.00 D) 11.0 E) 9.25 9) The average kinetic energy of the particles of a gas is directly proportional to A) the square of the rms speed 13) the square of the particle mass C) the particle mass D) the rms speed E) the square root of the rms speed 10) Arrange the following gases in order of increasing average molecular speed at 25‘C. C12, 02, F2, N2 A)Cl2 «c F2 4 02 c N2 B)Cl2 < 02 < F2 < N2 C)Clz «1 F2 < N2 < 02 [)le < 02 < N2 < C12 E)N2 < F2 < C12 4 02 11) A real gas will behave most like an ideal gas under conditions of A) low temperature and high pressure B) STP C) high temperature and low pressure D) low temperature and low pressure E) high temperature and high pressure 12) in the van der Waals equation, the constants a and b A) are equal to each other for any real gas B) are used to correct for the finite volume of gas molecules and the attractive forces between gas molecules. C) are used to correct for the difference between Celsius and Kelvin D) are equal to 1 for ideal gases E) are used to correct for the fact that collisions of gas molecules are not really completely elastic. 13) As a solid element melts, the atoms become and they have attraction for one another. A) more separated, less B) more separated, more C) larger, greater D) closer together, less E) closer together, more 14) The principal source of the difference in the normal boiling points of IQ (97C; molecular mass 162 amu) and 131-2 (59°C; molecular mass 160 amu) is A) London—dispersion forces B) hydrogen bonding C) dipole—dipole interactions D) both hydro gen—bonding and dipole—dipole interactions E) both dipole—dipole interactions and London dispersion forms 15) What is the predominant intermolecular force in CBr4? A) hydrogen—bonding B) ion—dipole attraction C) London—dispersion forces D) ionic bonding E) dipole—dipole attraction 16) What intermolecular force is responsible for the fact that ice is less dense than liquid water? A) London dispersion forces B) hydrogen bonding C) dipole-dipole forces D) ionic bonding E) ion—dipole forces 17) Of the following, is an exothermic process. A) freezing B) boiling C) melting D) sublimingJ E) All of the above are exothermic. 18) The vapor pressure of a liquid A) is totally unrelated to its molecular structure 13} increases linearly with increasing temperature C) decreases linearly with increasing temperature D) decreases nonlinearly with increasing temperature E) increases nonlinearly with increasing temperature 'I' 19) On the phase diagram below, segment corresponds to the conditions of temperature and pressurc under which the solid and the gas of the substance are in equilibrium. A) AC B) AB C) AD D) CD E} BC 1,000 800 P (torr) 600 400 200 0 -10 O 10 20 30 40 50 60 T (°C) 20} According to the phase diagram shown above, the normal boiling point of this substance is "C . A) U B) 10 C} 29 D) 38 E) -3 21] What fraction of the volume of each corner atom is actually within the volume of a face-centered cubic unit cell? 1 1 1 r 1 All B)—2- C)? D)g b)E 22) Gallium crystallizes in a primitive cubic unit cell. The length of the unit cell edge is 3.7031. The radius of a Ga atom is A) Insufficient data is given. B) 7.40 C) 0.930 D) 1.85 E} 3.70 23) Which of the following is not a type of solid? A) supercritical B) molecular C) ionic D) covalent—network E) metallic 24) A saturated solution . A) will rapidly precipitate if a seed crystal is added B} contains as much solvent as it can hold C) contains no double bonds D) contains dissolved solute in equilibrium with undissolved solid E) cannot be attained 25) Molality is defined as the A) moles soluteg’kg solvent B) moles solute I Liters solution C) moles solute/moles solvent D) moles solutefkg solution E) none (dimensionless) 71m- Nor 774—9 Emil). W9 W MﬁiﬂWﬁ—Lﬂ QUEZfr—‘gouf m M x ." KE‘ New poe/ 114.44" EKA‘IOA ? we mt ‘1 ( Mas Answer Key Testname: 114APRACTICEEXBSO4.TST MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) D [1): chcm9b an; 46 2) D E1}: (:hcm9b 10. —2'7 ’5) A JD: chem9b 10.1—29 11.): £thth '10! ~62 i1): {rhu'mE’h '10. ~66 1D: Chen'sz 111:8“ If}: (1.}.1em9h ‘IU.’ ~89 ED: chemE’b '10.'.~96 f}: (1-hem9la '10. .-'E(J9 J: trhmngh HIE. «122 II): rhetth 10.;435 '3: ("ha-3111913 'lU.1-'l4l] m}: cht‘n'lgb 1 1.1—3 - J: L‘hem9b 1'1 .I—IU 15) C “1): t.‘hcm‘.ib '.1 1.1-22 16 3 I): cheme 11.1-3” 17 A '3: (thome I'll—48 18 E .): l‘htrm§}1)'l1.1—?1 19 A J: chcm9b '11.1-?3 20 C : Che-111919 1.'l.Ii—8U r \J 21:) '1}; chume 113-24) My Answer Key Tesmame: 114APRACTICEEX3504.TST 22) D .ID: chezn9b 1.21 .'.1~95 23) A 1D: chi:me 111—109 24) D ID: (i11t!m9i)13.1—11 25) A 1D: chem‘Jb 13.1—53 11. The predominant interparticle force in CaBr2 is London—dispersion torces ionic bonding (:2 a) 1"“ b ion—dipole forces .14 ’ Ma? 6) 12. Molality 33.3%.} moles b} moles 032 c] moles {3) moles e) none 13: The vapor pressure of pure ethanol at 60QC is 349 torr. solution prepared by dissolving 10.0 mmol naphthalene (nonvolatile) in 90.0 mmol ethanol dipole-dipole forces hydrogen bonding is defined as the solute/moles solvent solute/Liters solution solute/kg solution solute/kg solvent {dimensionless} will have a vapor pressure of [93519 a) M 34.9 (61‘ 314 M8 c 600 d) 279 if, e) 69.8 14 AS and P. a) increases, 3 b] increases, c] decreases, HH+- CED decreases, decreases, fnuofafil'i the concentration of absolute in a solution increases, the vapor pressure of the solution increases decreases increases decreases is unaffected E Corr. He} _:: Pa 1 N ("I 3Lf‘jKo-6f a“_w §\$£' Raoult‘s Law predicts that a 240} “P A . Liner n- the freezing point of the solution '1 ;>ﬁwq-;”l~«JL- 22 Ct?‘ ow?»- Qu. 1. Most important for the engineer to understand is the relation between structure and properties of materials. Which statement is not true? (a) In metallic substances the electrical conductivity increases with increasing temperature whereas in semiconductors, it decreases. (b) Structural steels consist of a body centered cubic crystals separated by domains of pearlite structure. (a) The stable structure of tin at one atmosphere pressure and 25°C (room temperature) is metallic in character (white tin). (d) Duralumin is a structural material consisting of aluminum toughened by a fine dispersion of Al-Si compound. Qu. 2 Use the following graphs of free energy (per mole) of different phases of a pure substances to decide in which case does crystal A have a melting point of about 400°C? (L a liquid) a ( ) L; (d) a A s 500 1000 too 200 300 400 500 T (“Cl (2) L. 5 Fl 8 200 300 400 500 600 rue T (“Cl t 100 200 300 400 T (“Cl Que 3. In which of the ab0ve graphs (a)- (e)( Qu. 2) is the relation between solid phases most like the case of the metal iron? Qu. 4. An alloy of Fe and C contains 1.2 g of carbon and 56 g ofiron. What is the mole fraction of carbon in the alloy“? (3.) 0.021 (b) 0.50 (C) 0.12 (d) 0.09] Qu. 5. What is the temperature at which the fi rst crystals will start to form from the liquid solution during slow cooling? (a) 420°C (b) 440°C (c) 480°C (d) 570°C ' (e) 660°C Qu. 6. At what temperature will the last drop of liquid disappear? (3) 420°C (b) 440°C (0) 480°C (d) 570°C (6) 660°C Qu. 7. At which temperature(s) will the solid solution have the composition 20% B? (a) 610 (b) 550°C and 300°C (c) 550°C and 610°C (d) 550°C (e) 400°C ___________________——————-——- g diagrams are to be used for Qu. 8. The diagram for the iron + C system The followin extends only up to the composition Fe3C. On. 8. The cooling curve corresponds to which wt % carbon? (21) 0.4 (b) 0.8 (c) 3.2 (d) 4.9 (6) could be either (0) or (d) Qu. 9. Which ofthe following statements is false? (3) Carbon is much more soluble in FCC iron than in BCC iron. (1)) Cementite and martensite are both hard and brittle substances. (c) "Quenched and tempered” steels have excellent mechanical properties due to the presence of alternating layers of Fe3C and {1-th called pearlite. (d) Pearlite has a layered structure because diffusion in solids is intrinsically slow. Qu. 10. Consider the compositions (a), (b). (c). (d) and (e) marked at the base of the _ adjacent phase diagram. Which of these [ghom compositions when cooled slowly from the liquid state to room temperature, is most liker to have a microstructure like that shown in the circle below. FHC " wt Pin crm CARSON Qu 11.Which of the following is an incorrect statement? (a) The stable state of a system is the one with the lowest free energy (b) A system consisting of sugar crystals at the bottom of a glass containing water saturated with sugar has two phases and two components. (0) A system consisting of ice blocks floating in a sodium chloride solution has two phases and three components. (d) at room temperature and pressure, bcc iron is the state and phase of lowest free energy (e) In a two component system in which there is complete solid solution between the components, the two components must have the same crystal structure. ...
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