HW 6 KEY - CHM 2 0 4 6 HOMEWORK 6 Name SEC TA K E Z ‘6" 1 CHM 2046L Assignment 2 unknowns may contain any of these Nat K t(21‘ N03‘(a

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Unformatted text preview: CHM 2 0 4 6 HOMEWORK 6 Name SEC TA K E Z ‘6" 1. CHM 2046L Assignment 2 unknowns may contain any of these: Nat K+t (21‘, N03‘, . : @ (a) Which of these would have an effect on the RH of a solution of an unknown? What pH is expected (assuming 0.1 M and no other ion having a significant effect on the pH of water). Ion: :50!" gives pH = 1’2, Ion: "- gives pH = t :2 I Ion: “Half gives pH = Ion: Sng--Zgi\1res pH = -’I-,l{ ((er (b) List the two pH—incompatible pairs of ions. "Incompatible" means they could not exist together in the same solution, both in appreciable concentration, because they react With each other. 2H- and H or 014— and 1' 2. Human blood is closely buffered to 7.4 i 0.2, in part due to H2CO and Hc03‘. For H2CO3 in blood, use Kal a: B x 10‘7. kQ’:GJ a ( ) éalculate the concentration ratio [H2C031/{HC03"] for lood. } C€%§§J- [email protected]:[©el-sq 9') "" 00 ngé.3%g: O. 050 [HZCO31/[Hc03'] 0.08!) (b) How .\ ' the pH of arterial blood compare with that of venous blood? he or lower (circle one). Briefly indicate why. WY: (LO-L (c) What other CA/CB pair also helps to buffer blood? Select the best answer from the A/B handout (or read the list of contents on a bottle of Gatorade). CA = (K) r" CB = HPOEFQ' pKa 3. Look over the comprehensive solubility product table on page 823 to find the best Lewis base anion, in terms of its ability to bond strongly to a number of Lewis acids (metal ions), forming very sparingly soluble solids. Limit your search to anions listed as Bronsted bases on the class acid/base chart. What is the strength of this base, as a Bronsted base (strong, weak, or very weak)? What seems to be the next best Lewis base, again in terms of the low Ksp values of many of its salts? II II . - —- 'L _ Best Lew1s base: S Next best base: base strength smug base strength 544.0% Kb: mks m:wfll__fiw_% 4. A solution is formed by mixing 400. mL of l;0 M NH3 and 100. mL of 0.75 M AgNO3. The reaction Agf + 2NH3 e Ag(NH3)2 , Kf : l.6x107, goes essentially to completion. ' l i (a) What are the final concentrations of the pr1nc1pal species? _ £334 Wzmgfiuoo.) 080m +4.1“; oqgcmfifl’ CN‘X’Q TUB : +:‘NO":0_ '39: .w .. =CQ.3l-]§(~$ 8 O 0??!) 052$" [NH3] = 0.5’0N [Ag(NH3)2+] = OMSEI [N031 = OJS'M (b) Solve the Kf expression to find the small, "minor" [Ag+], _[@CN§)3*] _ 1:045; .,_ m— wave)" a W «m Ag = §,9/‘(0 5. Predict the signs ofAI-I and AS §+ or —t and the direction of equilibrium shift (R or L} at high and low temperature. You may use Appendix B tables, without actually performing any calculations, to find the signs offSH for each reaction. Forfiis, however, you should be able to “guestimate” the correct signs. E nation for Reaction H S low T hi h T 2N02(g) Z N204(g) (example) — — R L N2(g) + 202(g) Z 2N02(g) + '— L. L mm + 02(9) 2 2CO(g) ._ 4. 12 K 12(5) + C_12(g) z 21Cl(g) + +- L. ‘2 6. What is the value of the equilibrium constant for this reaction? Use available values of Rep (p 828) and Ka (handout). Cop,[email protected]~t)zt85 '53Cod’7v 4- L%3"K%:LZX£0:§ “Heed, w (5.5 Fig“ 4* JOm”) Kai-9X“) \ 23 lefo-‘LS ‘LQHO‘S ‘4 K 7‘ (R.’Lx[9"3 7- (6-‘5X10' Ca3(P04)2(s) + 4am: -—> 3 Ca+2 + 2321304‘ Additional Chapter 19 Problems: 44, '74, '77. Chapter 20 Study Problems: 5, '7, 1'7, 18, 29-33, 35. ...
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This note was uploaded on 03/27/2012 for the course CHM 2046 taught by Professor Veige/martin during the Spring '07 term at University of Florida.

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HW 6 KEY - CHM 2 0 4 6 HOMEWORK 6 Name SEC TA K E Z ‘6" 1 CHM 2046L Assignment 2 unknowns may contain any of these Nat K t(21‘ N03‘(a

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