test4solution_pdf

# 1 004 mol fe 2 002 mol fe correct 3 04 mol fe 4 02

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1. 0.04 mol Fe 2. 0.02 mol Fe correct 3. 0.4 mol Fe 4. 0.2 mol Fe Explanation: This is a 2 e process. mol of prod. = It n e F = (0 . 004) · (964 , 853) 2 · (96 , 485 . 3) = 0.02 mol Fe 016 3.0points The standard voltage of the cell Ag(s) | AgBr(s) | Br (aq) || Ag + (aq) | Ag(s) is +0.73 V at 25 C. Calculate the K sp for AgBr. 1. 3 . 9 × 10 29 2. 2 . 0 × 10 15 3. 5 . 1 × 10 14 4. 4 . 6 × 10 13 correct 5. 2 . 2 × 10 12 Explanation: 017 3.0points When a piece of paper burns, one could safely say, that is... 1. ...an oxidation-reduction reaction. CORRECT 2 . ... a neutralization process. 3 . ... an enzymatic reaction. 4 . ... Henderson’s hassle back. 5 . ... a Born-Haber reaction. Explanation: redox 018 3.0points For a zero th order reaction aA products

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Version 182 – Exam 4 – holcombe – (51395) 5 what is the y -intercept when the concentra- tion of A is plotted versus time to obtain a straight line? 1. - akt 2. akt 3. 1 [A] 0 4. ln[A] 0 5. [A] 0 correct Explanation: The equation is [A] 0 - [A] = akt [A] = [A] 0 - akt ( y = c - mx ) 019 3.0points For the cell diagram Pt | H 2 (g) , H + (aq) || Cu 2+ (aq) | Cu(s) , which reaction occurs at the anode? 1. H 2 (g) 2 H + (aq) + 2 e correct 2. Cu 2+ (aq) + 2 e Cu(s) 3. 2 H + (aq) + Cu(s) H 2 (g) + Cu 2+ (aq) 4. Cu(s) Cu 2+ (aq) + 2 e 5. 2 H + (aq) + 2 e H 2 (g) Explanation: 020 3.0points Express the rate of the following reaction in terms of the [SF 6 ]. 2 CH 2 S + 12 F 2 -→ C 2 F 4 + 4 HF + 2 SF 6 1. rate = - Δ[SF 6 ] 2 Δ t 2. rate = Δ[SF 6 ] 2 Δ t correct 3. rate = Δ[SF 6 ] Δ t 4. rate = - 2 Δ[SF 6 ] Δ t 5. rate = 2 Δ[SF 6 ] Δ t Explanation: rate = - [CH 2 S] 2 Δ t = - [F 2 ] 12 Δ t = [C 2 F 4 ] Δ t = [HF] 4 Δ t = [SF 6 ] 2 Δ t 021 3.0points A catalyst 1. operates only at high temperatures. 2. cannot be a biological molecule like an enzyme. 3. never occurs naturally; it is man-made. 4. must always be solid, as in a catalytic converter. 5. increases the rate of a chemical reaction but is not consumed in the process. correct Explanation: A catalyst increases the rate of a reaction by providing an alternative mechanism with a lower activation energy. It may participate in some parts of the reaction but by the end of the overall reaction it is regenerated. Cat- alysts may be in any state (solid, liquid, or gas). Enzymes are biological catalysts. 022 3.0points For the reaction cyclopropane propene a plot of ln[cyclopropane] vs time in seconds gives a straight line with slope - 4 . 1 × 10 3 s 1 at 550 C. What is the rate constant for this reaction?
Version 182 – Exam 4 – holcombe – (51395) 6 1. 1 . 8 × 10 3 s 1 2. 2 . 1 × 10 3 s 1 3. 4 . 1 × 10 3 s 1 correct 4. 8 . 2 × 10 3 s 1 5. 3 . 9 × 10 2 s 1 Explanation: 023 3.0points A certain reaction has a rate constant of 8 . 8 s 1 at 298 K and 140 s 1 at 323 K. What is the activation energy for this reaction? 1. 38 kJ · mol 1 2. 89 kJ · mol 1 correct 3. 23 kJ · mol 1 4. 120 kJ · mol 1 5. 1 . 2 kJ · mol 1 Explanation: 024 3.0points Consider the concentration-time dependence graph for two first-order reactions.

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