2008_06_03_13_18_52

2008_06_03_13_18_52 - Practice test 2-2-2001-(old...

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Unformatted text preview: Practice test 2-2-2001-(old 2004)------FOR EACH OF THE 20 QUESTIONS. GIVE THE BEST ANSWER OR THE CLOSEST NUMERICAL; FILL IN YOUR STUDENT ID NUMBER. NAME. AND TEST FORM=A 1. Shown below is a phase diagram for sulfur (not drawn to scale). Sulfur can exist in solid modifications, rhombic and monoclinic. denoted by SR and SM. respectively. Which of the following statements (a-d) is incorrect? t pressures close to 1 atm. rhombic sulfur can be in stable equilibrium with liquid sulfur; At a given pressure. there is (at most) one temperature at which rhombic sulfur can exist in equilibrium with monoclinic sulfur; (e) None of these statements is incorrect. film system has two triple points; (b) Under ordinary atmospheric conditions (at sea level). sulfur docs not sublime; statements islare true? More than one statement may be true. (a) X can exist as a gas at temperatures lower than 20°C. (b) Solid X will sublime if heated in a container that is open to the atmosphere. (0) X has a normal boiling point above y 2. Suppose that a certain substance (X) has a triple point temperature of 20°C at a pressure of 2.0 atm. Which of the following art 20°C. (d) Noneof the three statements is true. t least two of the statements are true 3. A non-volatile solute added to a solvent raises the boiling point of the solution relative to the solvent because... (a) The temperature to cause boiling must be eat enough to boil the solute as well as the solvent. (b) The solute particles raise the solvent's vapor pressure. @T he solute particles lower the solvent's vapor pressure. (d) The added solvent increases the mass of the solution an higher temperature is needed to boil the greater mass. (e) The boiling point of the solution is a mole weighted average of the solute and solvent boiling points. 4. Which of the Ilowing has the boiling p int below 200 C and is very soluble in water”? (a) CCI4: ((Cb) CH3 CH2CH2NH2: Pb; (d) NaF; (e) NaBr 5. Rank the following compounds according to increasing solubility in water. I. CHz-CHz-CHz-CHai IL CHa-CHz-rO—CHz-CHai I". CH3-(CH2)3-NH3; IV. CHa-OH (A) I < lll < IV< II; (b) I < ll < IV< Ill; (c) I||< IV< ll < I; (@l < II < lll< IV; (e) No order is correct. 6. Place the following in order of incre ’ vapor pressure: CCIZFZ. CCl4. CH3C00H: (a) CCIIQF < CCl < CH3C00H; CH3COOH< CCt4< CC<I§F2; (c)CCI4< CH3COOH<CC12F2; H . (d) 002 2< CH3 OOH < CCI4: (e) CCl4 < CCIZFZ < CH300 7. Which of the following is the minimum amount of information that you need in order to calculate the freezing point of a 1 single. nondissociating solute in a solvent. 6 molality (of the solute in the solution): (b) the molality plus the freezing ‘ 1 m point depression constant of the solvent; , c) at the information in b plus the freezing point of the pure solvent: (d) all the information in c plus the molecular weight the solute; (6) all of the information in c plus the weight of the solvent 9. Calculate the molecular weight of a salt X+Y- if a 6.66 9 sample dissolved in 666' mL of water has an osmotic pressure of 666 mmHg at 25.0 °C. (R = 0.0821 L-atm/mol-K: 760 mmHg = 1 atm). Assume the solution is ideal. (a) 26 glmol: (b) 55 glmol: (c) 110 glmol: (d) less than 229Imol; @Ol‘e than 130 g/mol %:1Q0831)(19$)C ‘ _ h CF 760 ul’rt‘l _. s c J .gqg‘; : “(3”? .E'Ub ‘ ooi'L V\:.ul‘t‘l 'O‘IM‘A'U 9. If a 6.66 9 sample of an electrolyte X‘“2\("l is dissolved in 666 g of water. the resulting solution will freeze at -0.838 °C. (K = 1.86 °Clm). Estimate the formula weight of XY in glmol. (a) about 22: ( ) a bit less than 44; (c) a bit more than 44; (@a bit less than 66 (e)A bit more than 66 v y , I I. we ~. 3% or I-i -‘ Mm mwésrl. ~33“ mower. 3 v °‘ ' *fi : some M,- m .m (MHde )4: v. ( ,3)..— 1 $3” . (5 J 10. Which of the following will have the lowest total vapor pressure at 25°C? (x = mole fraction). (a) Pure H20 [P°(H20) = 23.8 torr at 25°C]; (b) A solution of glucose In H20 with Xgmm = 0.01: @A solution of NaCI in H20 with mac. = 0.01: (d) A solution of CH3CH20H in H20 with ammo” = 0.2; (e) Two are tied for the lowest vapor pressure (7 '— YHto YMWO O (7 '. \‘ (-tLo Y ‘LLLE 4 l l K = 1.2 x 10‘30 atm for the reaction: 2Hg0(s1) <---> 2Hg(la+ 02(g). Calculate KP in mm”2 for the reaction 2 91 1302(9-1' Hg(l) <-.> Hg0(s). @J x 101 ; (b) 8.3 x 10 9; (c) 1.1 x 10-15; (d) 4.2 x1029; (e) -1.1 x 10-15 ,(‘KP>."1: ‘1 “041572, 12 At 21.8°C, Kc = 8333 for NH3(g) + H25(g) <u> NH4HS(s). What is the concentration of NH3 at equilibrium if a solid sample of NH4HS is place in a closed vessel at 21.8°C? (a) .1 x 10'2 M; (b) 1.2 x 10'4 M; (c) 5.5 x 10‘3 M; (d) 2.2 x 10'2M; ._ 1:0 (J 1 o -. Wm, : -— x K Y J 70. V 1’1 ‘00 X: 1111(1). (e) 4.4 x 10‘2M 2. 13. Initial pressures of P(NO) = 98.4 torr and P(Br2) = 41.3 torr were allowed to react at an unknown temperature. At equilibrium P(total) = 1 10.5 torr. calculate the K in units of torr'l for the reaction 2N0(g) + Br2(g)<--> 2NOBr(g). (a) 14.6; (b)s.5x10'3; (c)o.o45/ (d) .18; (5)6.7x10'3; “191‘ :46 0 , rs .14)" , x K - )3:— ‘:1"}lg Ho‘g : Q1 8.141%)4 l 0rl.1~v)r‘2.‘/ -Z‘IL \>< lx 4» til-UN r «.1- 7c “raw—2;; “ “1" F1 to [§‘\ Cx‘kr‘ f3 ‘ ’ '14 For the reaction, 2802(g) + 02(g) <--> 2803(g), at equilibrium, what is the relationship between the reaction " v A 7 l / 9 ‘6. quotient (Q) and e equilibrium constant (Kc) at the moment 1 atm of excess 02(g) is added? (a) Q = KC; 3 ) < Kc; (c) Q> Kc; (d) Q 2 Kc; (e) need to know the value of K and initial concentrations pndo ‘zfie 'O‘ttalg‘.)\y.c\5 “IAN 70,0V\'~.M':1, K? , T? , ‘V 15 Consider the following reaction: 0ng <->2Cl(g). What conditions favor the production of chlorine atoms, Cl(g), i.e. increase the [Cl]/[Clz] ratio? (hint: you need to figure out if it is an exo/endothermic reaction.) @ugh T and low P; (b) high T and high P; (c) low T and low P; (d) low T and high P; (e) low T and a small container volume. ( i 16 For the exothermic reaction, 2C02(g) <--,>2C0(g) + 02(3), adding more 02(g) to the system at equilibrium will (a) increase the [CO]e ; (b) decrease [C02]eq; (c)increase Kc; {(dTEause the reaction to shifi to the left; (e) cause heat to be released. ' a g; o 1 <-‘ (0’ 3 C0 2‘? K View; fix; SAW. I I 17 For the exothermic reaction, 2C02(g) <--,>2C0(g) + 02(g), which one of the following will cause an increase in the value of the equilibrium constant for a reaction? (a) an increase in volume; (b) addition of C02; (c) increasing the temperature; (d) increasing the temperature or addition of C02 ((EFone of the above 138 For which of the following types of reactions would one expect the equilibrium constant to increase with increasing temperature and have an appreciable amount of products near 300 K. g (a) AH° >.o, AS° >> 0 ; (b) AH° > o, as° << 0; WAH°< 0, A80 >>o; m0 < 0, 415° << 0 or AS° >> 0; " (e) AH° > 0, A80 >> 0 or as° << 0 ‘ v .1 0,9”) k ,7 e r;\ Fir ag‘T?$J Abid7o 19 Consider the following reaction: 802C12(g) <--> 802(g) + C12(g). At equilibrium at 200 ($6111?) .OO-L container. [SOZCIZI = 0.80 M, [802] = 0.20 M, and [C12] = 0.20 M. If an additional 0.20 moles of 802(g) isadded, calculate the new concentration of |SOZC12| at equilibrium (hint: calculate Kc first). (a)0.60; (b) 0.73; (c) 0.80;\(d) 0.87; (e) 1.0 - ‘CYC ‘2. t4: (11>(IZ> A 77 1711‘"... (1'4"(\(‘)"¥) 0( ,. q/"é‘ [qr . IVZU i. f I. ‘05 ' )U7L11 Live 1 ' " .q 1 \gflt‘(\ I J a is r 1 ‘ » ac ix 1 , \k I 7 L V121 ~qu 1.1 4 0M“ ‘ 7"”‘3 20 1 atm of N2 and 3 atm of H2 are mixed at' 500 JC; they produce ammonia: NH3(g) <-->1/2 N2(g), 13/2 H2(g). The equilibrium total pressure is 2.12 atm. Calculate the equilibrium pressure of NH3 in atm. (100.601; (b) 0.180; @88; (d) 0.940; (e) 0.0601; ');“7_ ‘ 4 _‘ W" r when—item) V A.” ‘r 1.‘_“/2_ 1t,.{\( 21 What characteristic of cats is shared by communists? (a) Lazyness; (b) Sense of entitlement; (c) Great tendency towards adultery; (d) Hairy; (c) all of the above but these things are more common in cats than commies FILL IN YOUR STUDENT ID NUMBER, NAME, AND TEST FORM=A ...
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This note was uploaded on 07/15/2008 for the course CHEM 6A taught by Professor Pomeroy during the Fall '08 term at UCSD.

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2008_06_03_13_18_52 - Practice test 2-2-2001-(old...

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