Chemistry Problem Set: Equilibrium Constants and Reaction Rates, Exams of Chemistry

Download Chemistry Problem Set: Equilibrium Constants and Reaction Rates and more Exams Chemistry in PDF only on Docsity! CHEM: 113 - Dr. Boyd f Name please print Sec. 45 March 17, 1999 \ ^ No.____ T.A. |c ********************** In all problems the method must he clearly shown. All numerical answers must be expressed using the correct number of significant figures. Ka : HOAc... 1.8 x 10~5 Kb : NEUOH... 1.8 x lO' 8 Ksp: Ag2CrO4 ... 1.20 x lO' 12 Hg2 SO4 ... 7.41 x 10~7 ****************************************************************************************** 1. Your assigned number in its proper place. (2) 2. A. Write the formulae of B. Write the names of (4) i) i) ii) ii) 3. A. List the three factors which, in general, affect the rate of a reaction. (3) i) " iii) ii) B. As in class, define catalyst. (2) 4. A 0.10 MHX solution is 0.050% ionized. Calculate Ka for HX. (6) Ans 5. Calculate the concentration of HO Ac so that the pH is 2.57. (6) SCORE 1. ____ 2. ____ 3. ____ 4. ____ 5. ____ 6. ____ Ans__________ M 6. Calculate the pH of water at 0.0°. At 0.0°, Ka = 1.2 x lO" 15 . " (6) Ans 7. A solution is 0.75 M with respect to NH4OH and 0.50 M with respect to NHLjCl. (12) A. Calculate the pOH of the solution. Ans B. To 650 mL of the solution is added 150 mL 0.30 M NaOH. Calculate the pOH of the (new) solution. Assume AV = 0. Ans 8. Calculate the pH of a solution made by mixing 250 mL 0.250 M NaOH with 375 mL 0.600 M (6) HOAc. Assume AV = 0. Ans -2- 16. Consider 2 H2O2 + 2 I- + 2 H+ -> 12. +. 2 H2O Initial concentration mol'L" 1 Initial rate [H202] 0.010 0.020 0.010 0.020 B-] 0.010 0.010 0.020 0.010 [H+] 0.00050 0.00050 0.00050 0.0010 1.15 x 10-6 2.29 x 10-6 2.31 x 10-6 2.30 x 10-6 rate = k[H2O2] m [I'] n [H+]° A. From the above data m = n = (6) B. The units of k are. (2) -5- X2(g) + 2Y-> 2XY(g) Initial RateInitial Concentration mol'L'l X v ' i 0.20 0.20 0.40 0.20 0.80 0.20 1.2xlO-4 4.8 x 10-4 2.4 x 10-4 (6) Proposed mechanisms A. X2(g) + 2Y(g) -* 2XY(g) B. X2 -> 2X X + Y -> XY slow fast C. X2 + Y X + Y XY XY slow fast D. X2 + 2 Y YXXY YXXY 2XY slow fast E. 2Y -» YY X2 + YY -> YXXY YXXY -> 2X slow fast fast F. X2 + Y -> XXY Y + XXY -> 2XY slow fast Write the number of the statement below which best fits the above data. 1. A is an acceptable mechanism. 2. B is an acceptable mechanism. 3. C is an acceptable mechanism. 4. D is an acceptable mechanism. 5. E is an acceptable mechanism. 6. F is an acceptable mechanism. 7. B and C are acceptable mechanisms. 8. C and E are acceptable mechanisms. 9. C and F are acceptable mechanisms. 10. D and E are acceptable mechanisms, 11. C, E and F are acceptable mechanisms. 12. None of the above mechanisms are acceptable. Ans -5-