Homework 10 - ycs73 Homework 10 Fakhreddine (53605) 1 This...

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Unformatted text preview: ycs73 Homework 10 Fakhreddine (53605) 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Under certain conditions, the reaction 3 A + 2 B 4 C was observed to proceed at a rate of . 00223 M s 1 . What was the corresponding rate of change in reactant A? 1. . 001115 M s 1 2.- . 00446 M s 1 3. . 00446 M s 1 4. . 000743333 M s 1 5.- . 001115 M s 1 6.- . 00223 M s 1 7. . 00223 M s 1 8.- . 000743333 M s 1 9.- . 00669 M s 1 correct 10. . 00669 M s 1 Explanation: Reactant A is reacting at 3 times the stated rate of the overall reaction. A is also a reac- tant, so the concentration is DECREASING with time, which corresponds to a NEGA- TIVE rate. 002 10.0 points The reaction N 2 + 3 H 2 2 NH 3 is proceeding under conditions that 0.150 moles of NH 3 are being formed every 20 sec- onds. What is the rate of disappearance of H 2 ? 1. 2 . 25 10 1 moles/sec 2. The question cannot be answered from the information given; we need to know the rate law for the reaction. 3. 7 . 5 10 3 moles/sec 4. 1 . 125 10 2 moles/sec correct 5. The question cannot be answered from the information given; we need to know the volume of the container. Explanation: n NH 3 = 0.150 mol t = 20 s The rate of appearance of NH 3 is Rate = 1 2 [NH 3 ] t We can consider this to be Rate = 1 2 . 150 mol 20 s = 0 . 00375 mol / s The rate of disappearance of H 2 is Rate =- 1 3 [H 2 ] t . 00375 mol / s =- 1 3 [H 2 ] t [H 2 ] t =- . 01125 mol / s Thus H 2 disappears at a rate of 1 . 125 10 2 mol/s. 003 10.0 points The following data were collected for the re- action 2 A + B 2 + C D Initial Initial Initial Initial [A] [B 2 ] [C] rate (M) (M) (M) (M/s) 1 . 01 . 01 . 01 1 . 250 10 3 2 . 02 . 01 . 01 5 . 000 10 3 3 . 03 . 01 . 05 1 . 125 10 4 4 . 04 . 02 . 01 8 . 000 10 4 Find the rate law. ycs73 Homework 10 Fakhreddine (53605) 2 1. Rate = (1 . 25 10 9 ) [A] 2 [B 2 ] 2. Rate = (1 . 25 10 9 ) [A] [B 2 ] 2 3. Rate = (1 . 25 10 7 ) [A] 2 [B 2 ] 2 4. Rate = (1 . 25 10 7 ) [A] [B 2 ] [C] 2 5. Rate = (1 . 25 10 11 ) [A] 2 [B 2 ] 2 correct Explanation: Rate = k [A] x [B 2 ] y [C] z Rate 2 Rate 1 = k [A] x 2 [B 2 ] y 2 [C] z 2 k [A] x 1 [B 2 ] y 1 [C] z 1 5 . 000 10 3 1 . 250 10 3 = parenleftbigg . 02 . 01 parenrightbigg x parenleftbigg . 01 . 01 parenrightbigg y parenleftbigg . 01 . 01 parenrightbigg z 4 = 2 2 = 2 x x = 2 Rate 4 Rate 1 = k [A] 2 4 [B 2 ] y 4 [C] z 4 k [A] 2 1 [B 2 ] y 1 [C] z 1 8 . 000 10 4 1 . 250 10 3 = parenleftbigg . 04 . 01 parenrightbigg 2 parenleftbigg . 02 . 01 parenrightbigg y parenleftbigg . 01 . 01 parenrightbigg z 64 = 4 2 2 y 2 y = 64 16 = 4 = 2 2 y = 2 Rate 3 Rate 1 = k [A] 2 3 [B 2 ] y 3 [C] z 3 k [A] 2 1 [B 2 ] y 1 [C] z 1 1 . 125 10 4 1 . 250 10 3 = parenleftbigg...
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This note was uploaded on 04/15/2009 for the course CH 53625 taught by Professor Fakhreddine during the Spring '09 term at University of Texas at Austin.

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Homework 10 - ycs73 Homework 10 Fakhreddine (53605) 1 This...

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