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chm 2046 exam 2 f07 - ”7(57[EX Z FL“ fir 41’ F0 cm W...

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Unformatted text preview: ”7(57 [EX Z FL“ fir 41’; F0 -. cm W M... 7 ’7 <97 ofj X320». % CHM 2046 EXAM 2, FORM CODE A Oct. 19, 2007 Please bubble in A as the test Form Code at the top right of your answer sheet. Failureto do this will result in a penalty of 10 points. 1. In the eqn for the chemical rxn at 25 °C which corresponds to AG;i for calcium sulfate dih drate sum , the total number of moles of reactants is y (gyp ) awe/1‘ 3%.!“ W (1) 34/7 (2) 6.442 (3) 49/2 4) w... 5 7.320. ; ““— Ws. w W” “e 2. Of the following solns at 25 °C, CaSO4-2H20 s s o a e most soluble in (1) 0.5 M 3152304 (2) 0.3 M KHso4 @5 M H2SO4 (4) 0.4 M (35.012 (5) 0.7 M (NH4)2SO4. 3. Consider: H20(g) —+ H20(s). If this process is spontaneous, then (1) Patmospheric > 1 tm & T = 0.0 °C (2) PH20(g) < VP H20(s) 85 T < 0.0 °C (3)AGis+or— 6 His—,ASis— (5)AHis+,ASis—l~. 4. For: CaSOi-2H20(s) + HOCOz_(aq) + HS*(aq) x——‘ Ca003(s) + HQS(aq) + SO42‘(aq), K is closest to (1) 3.3x103 (2) 5.2x10'4 (3) 123 (4) 0.091 (3,1934. 5. If 0.014 L of 0.25 M HF is mixed with 12.5 mL of 0.28 M NH3 the resulting 3011] will be 1 mildly basic (2) neutral (3) strongly acidic (4) strongly basic (5 ildly acidic . 6. Eff, at 25 c’C, for: C(diam) x=‘ C(graph), AGE : — 2.9 Id, 3" = 5.74 J/mol K for C(graph), . and 8° 2 2.38 J/mol K for C(diam), AH; for C(diam) is closest to (1) + 2.3 kJ/mol (2) — 3.4 kJ/mol W 0.35 kJ/mol @]+ 1.9 111/5551 (5) — 1.2 kJ/mol. @he most exothermic of the following rxns is (1) H20) + 1/2 02(5) —+ H200) $04.2 H20) + 02(5) —> 2 H200) (3) H20) + 1/3 0.13) —> H200) (@i H20) + 2/3 0.0) —> 2 H200) (5) 2 H2(3) + 2/3 03(3) —> 2 H20(e)- 8. If for an aqueous HO)2802 soln, [H30+] = 4[HOSO3‘], Mi (HO)2S02 is closest to 0.0025 M 0.0050 M (3) 0.0018 M (4) 0.012 M (5) 0.0072 M. 9. he following listed semi- -soluble salt whose solubility in water is least reliably estimated $131" 1y fI'Om its Ks sp is (1) gCN NaSO4() ()3 CaF2 MSfiOHh KPI-IggBrg- at onsider the formation of water from its elements at - 10 °CP ext :1 atm. For this rxn it ue that |AH§ | H200) > IAHH H 0(3) @113”) H20(s) > [AG°[ H20(S ) ESQ prod > Z: Sfeact We: is + (5) AH1?_ _ 0' 11. For: 2 Fe304(s) + 002(g) —+ 3 F8203(S) + CO(g), AHr 3: 48.5 kJ. For: FeO(s) + CO(g) —-+ Fe(s) + 002(g), AB} = 11.0 kJ. For. 2Fe(s ) +3002(g )—>Fe203(s s) +3CO(g ) AH =fl20.5kJ Based on these data, for: 3 Fe0(s) + 002(g) —> Fe304( (s) + 00(g), AH is closest to ()1 —24.5kJ (2)—19.5kJ (3)195k1 @1122011 (5)245kJ. @fifli e following rxns at 25 ”C AG“ is “+11 for NH4 ()aq )‘9+AC( 9&9)->HAc( )+NH3(a,q) Ca2+( (3(1) + 2 F (aq) —> came.) K0101) —> K+( aq) + 01- (aq) (4 001030) -|— H200) _) H3O+(aq) + 0104—(aq) (5) C9(0H)2(9) + SOB—(m) + 2 H200) —> CaSO4-2H20(s) + 2 HO'(aq). 42,11 2:4 2 FC .4 L14 Pa? £1244 hora m 13. For: 2 03(g) x=‘ 3 02(g), the thermodynamic K has units of (1) atm—1 (2) 11/!2 @atm (4) M—1 (5) M/atm. ‘or the following listed reagents, conversion of CaCO3(s) into gypsum, CaSO4-2H20(s), is most effectlvely ach1eved by treatmg 08.003 (3) w1th an excess of (1) 1 M N82304 BBSO4(S) k M (NH412804 (4) 1 M K2804 85 1 M H001 (5 M F82 (80403 . @113, for a buffered, saturated, aqueous sol-n of 03.003, it is found that [Ca2+] >> [0032‘] and [Ca2+] = 21116093021, the soln has been buffered at a pH closest to 2 (1) 10.0 ' .. .4 (3) 11.4 %8.5 (5) 4.7. 16. Consider: A12(SO4)3 (s) -—) A1203(S ) + 3 303(g). At 25 °C this rxn comes to EQ with a K of 4. 6 x 10 70 atms. Based on this, if excess A12(SO4)3(s) decomposes at 25 0C until EQ is achieved 1n a room with a volume of 1. 0 x 1010 L, the number of 803 molecules produced will be closest to @2 x 109 (2) 2 >< 101° (3) 2 x108 (4) 2 x 1012 (5) 2 x1011. @or: 2 Ag+(aq) + 2 HO‘(aq) # Ag 9(5) + H20(1), K equals ‘ (1) KSP(AE2O) MKMAMO) x Kw @1/K3P(Ag20) ' (4) 1/K8p(Ag2O) x “Kw ( 1 sp(AgOH)- 18. For a dilute, aqueous H2804 soln in which HSO4‘ is ionized to an extent of ~ 50%, the correct charge-balance eqn for principal species is (1) [1130+]: [Ho- ] (2) 2[H30+1=[HSO4_1+[SO42_1 69?}; was [H304 1+ [8042‘] +[H0‘] (4) [H30+]=[H304‘l+13042‘l 30+1— — [H804 1+ +2[SO42_1 . 19. Consider: C( (diamond) + 02(g) —> COg(g ). At 25 °C this rxn comes to EQ with a K of 3. 6 X 1059. Based On this if 106 g of diamond stands in the Open atmOSphere of CLB 130 (volume is 107 L) until EQ is achieved, the quantity of 002 produced by this rxn will be closest to (1) 0.29 mols (2) 13 mols @9.3 x 104 mols (4) 3.7 x 103 mols (5) 6.1 x 109 mols. @For: AgCl(s) + 2 NH3(aq)—" Ag (NH3)2+(aq) + Cl (aq), K 13 0.0029. Therefore, if for this sy cm at EQ, [Ag(NH3)2+ 1 z 0.20 and [05(0. .31 M for NH3 was closest to 4 ( 1.2M @.0M>i)\ 6.4M 0M MLM W} 21 If a soln is prepared by mixing 60.0 mL of 0.35 M NH4Cl with 70. 0 mL of 0. 40 M NH3, and 0.11 mols HCl( (g) IS bubbled into this soln, [H30+] 1n the resulting soln will be closest to ()1 0.24M (290.63M (3) 0.77M (4) 0.0043M (5) 0.0.0029M he solubility of Ca003 is reliably estimated strictly from its K3,, if Ca003 IS saturated' 1n ‘ (1) 1 M NH4CI 61:1 M Nags (3) 0.01 M “H 2003” 134 pure water (5) 0.5 M A12(SO4)3. 23. Indicator HIN is yellow (Y) at pH 2.7 or less, green (G) at pH 3.7, and blue (B) at pH 4.7 or above. So, if 100 mL of 0.1 M HX is treated with a drop of this indicator to give a GB color, it follows that as B /L acids (1) HX is much stronger than HIN (2) HX is slightly stronger than HIN (3) HX and HIN are about the same strength @1111 is much stronger than HX (5) HIN is slightly stronger than HX. @5191: Ca(Ol-I)2(s) + 8042*(aq) \——‘ CaSO4-2H20(s) + 2 HO‘(aq), K = 3.6 at a particular .,80 if at this T, 1. 0 mols Ca(0H)2(s) is shaken in 1.0 L of 1.0 M Na2804 and the liquid sy em volume em us at 1. 0 L, the [HO] resulting on es ablishing EQ is closest to 1.0M [email protected] fl0.80M( (5 ISM-W147 ...
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