Homework 11 Solutions

# Homework 11 Solutions - Gadhia Tejas Homework 11 Due Dec 5...

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Gadhia, Tejas – Homework 11 – Due: Dec 5 2007, 11:00 pm – Inst: James Holcombe 1 This print-out should have 28 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. The due time is Central time. 001 (part 1 oF 1) 10 points ±or a reaction that is zero-order overall, 1. the reactant concentration does not change with time. 2. the rate constant is zero. 3. the rate does not change during the reac- tion. correct 4. the activation energy is zero. Explanation: Remember that For a zero order reaction, the reactant is still used up; its concentration will decrease as time passes, but the rate will not be a²ected. IF you double or triple the concentration oF that reactant, the rate will not change For a zero order reaction. 002 (part 1 oF 1) 10 points The rate oF the reaction 2 O 3 3 O 2 is equal to 1. - 1 3 Δ[O 2 ] Δ t . 2. - Δ[O 2 ] Δ t . 3. - Δ[O 3 ] Δ t . 4. + 1 2 Δ[O 3 ] Δ t . 5. - 1 2 Δ[O 3 ] Δ t . correct Explanation: The rate oF a chemical reaction can either be expressed as the rate oF disappearance oF a reactant (as in this case) or as the rate oF appearance oF a product. However, this rate is multiplied by the inverse oF the coeF- fcient oF the species in question. The nega- tive sign here reminds us that as the reaction progresses, this species is consumed and de- creases in concentration. 003 (part 1 oF 1) 10 points When we speak oF the rate oF a reaction, we are reFerring to 1. the average rate. 2. the maximum rate. 3. the integrated rate. 4. the minimum rate. 5. the instantaneous rate. correct Explanation: Reaction rate varies as a reaction pro- gresses, slowing down as the amount oF re- actant decreases. The instantaneous rate is the rate at a particular time. 004 (part 1 oF 1) 10 points Consider the elementary reaction H + Br 2 HBr + Br The rate oF production oF HBr would be reliably aproximated as simple frst order iF 1. [H] is small and [Br 2 ] is small. 2. [H] is large and [Br 2 ] is large. 3. [H] and [Br 2 ] are about equal. 4. [H] is small and [Br 2 ] is large. correct 5. frst order will never be a good approxi- mation. Explanation: The very small amount oF H will be con- tinuously used up, displacing one oF the Br atoms and Forming HBr.

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Gadhia, Tejas – Homework 11 – Due: Dec 5 2007, 11:00 pm – Inst: James Holcombe 2 005 (part 1 of 1) 10 points Consider the reaction 2 NO 2 (g) + F 2 (g) 2 NO 2 F(g) rate = - Δ[F 2 ] Δ t . What is another form of the rate of the reaction? 1. - Δ[NO 2 ] Δ t 2. Δ[NO 2 F] Δ t 3. - 2 Δ[NO 2 ] Δ t 4. Δ[NO 2 ] 2 Δ t 5. Δ[NO 2 F] 2 Δ t correct Explanation: 006 (part 1 of 1) 10 points For the reaction 2 NO(g) + 2 H 2 (g) N 2 (g) + 2 H 2 O(g) the following data were collected. [NO(g)] [H 2 (g)] Rate, M/s 0.10 0.10 0.0050 0.10 0.20 0.010 0.10 0.30 0.015 0.20 0.10 0.020 0.20 0.20 0.040 What is the rate law for this reaction? 1. None of these 2. rate = k [H 2 ] [NO] 2 correct 3. rate = k [H 2 ] [NO] 4. rate = k [H 2 ] [NO] 5. rate = k [H 2 ] [NO] 2 6. rate = k [H 2 ] 2 [NO] Explanation: 007 (part 1 of 3) 10 points Manganate ions (MnO 2 - 4 ) react at 2.0 mol L · min in acidic solution to form per- manganate ions and manganese(IV) oxide: 3 MnO 2 - 4 (aq) + 4 H + (aq) 2 MnO - 4 (aq) + MnO 2 (s) + 2 H 2 O( )
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Homework 11 Solutions - Gadhia Tejas Homework 11 Due Dec 5...

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