1 ( 20% ) Consider the following for the formation of a DNA double helix from its strands A and B: A + B → unstable helix ( fast ,k1 and k1' ) ← Unstable helix → stable doubl helix (slow,k2) Derive the rate equation for the formation of the stable double helix and express the rate constant of the overall reaction in terms of the rate constants of the individual steps. 2 ( 7% ) The rate constant of the reaction O(g) + N2(g) → NO(g) +N(g), which occurs in the stratosphere, is 9.7 * 10^10 L mol^(-1)s^(-1) at 800 度c . the activation energy of the reaction is 315 kJ mol^(-1). Determine the rate constant at 700 度c 3 ( 8 % ) Determine the rate constants for the following first-order reactions: (a) A→B,given that the concentration of A decreases to one-half its initial value in 1000s. (b) 2A→B+C,given that [A]0=0.153 molL^(-1) and that after 115 s the concentra- tion of B rises to 0.034 mol L^(-1) 4. ( 18 % ) A. Write the shortened ( condensed ) structural formula of (a) ethylbenzene (b) 2,3,5,-trimethylheptane (c) 2-ethyl-1,1,-dimethylcyclohexane B.Indicate which molecules display optical activity and indicate the chiral ca rbon atoms in those that do (d) CH3CHBrCH2Ch3 (e) CH3CH2CHCl2 (f) CH3CH(OH)CH2CH3 5.( 7% ) What are the possible products for the reaction of sodium ethoxide (NaOCH2CH3) with (a) 1-bromobutane (b) 2-bromobutane 先打一頁 還有 3 頁 --

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