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Chemistry LibreTexts

Homework 3 (Due 4/11/16)

  • Page ID
    47371
  • Name: ______________________________

    Section: _____________________________

    Student ID#:__________________________

    Q3.1

    Describe how graphical methods can be used to determine the order of a reaction and its rate constant from a series of data that includes the concentration of A at varying times.

    Q3.2 (New)

    A study of the rate of the reaction represented as \(2A⟶B\) gave the following data:

    Time (s) 0.0 5.0 10.0 15.0 20.0 25.0 35.0
    [A] (M) 1.00 0.952 0.625 0.465 0.370 0.308 0.230
    1. Determine the average rate of disappearance of A between 0.0 s and 10.0 s, and between 10.0 s and 20.0 s.
    2. Estimate the instantaneous rate of disappearance of A at 15.0 s from a graph of time versus [A]. What are the units of this rate?
    3. Use the rates found in parts (a) and (b) to determine the average rate of formation of B between 0.00 s and 10.0 s, and the instantaneous rate of formation of B at 15.0 s.

    Q3.3

    Compounds A and B both decay by first-order kinetics. The half-life of A is 20 minutes and the half-life of B is 48 minutes. If a container initially contains equal concentrations of compounds A and B, after how long will the concentration of B be twice that of A?

    Q3.4

    Nitrosyl chloride, NOCl, decomposes to NO and Cl2.

    \[\ce{2NOCl}(g)⟶\ce{2NO}(g)+\ce{Cl2}(g)\]

    Determine the rate equation, the rate constant, and the overall order for this reaction from the following data:

    [NOCl] (M) 0.10 0.20 0.30
    Rate (mol/L/h) 8.0 × 10−10 3.2 × 10−9 7.2 × 10−9

    Q3.5

    Hydrogen reacts with nitrogen monoxide to form dinitrogen monoxide (laughing gas) according to the equation:

    \[\ce{H2}(g)+\ce{2NO}(g)⟶\ce{N2O}(g)+\ce{H2O}(g)\]

    Determine the rate equation, the rate constant, and the orders with respect to each reactant from the following data:

    [NO] (M) 0.30 0.60 0.60
    [H2] (M) 0.35 0.35 0.70
    Rate (mol/L/s) 2.835 × 10−3 1.134 × 10−2 2.268 × 10−2

    Q3.6

    Use the data provided to graphically determine the order and rate constant of the following reaction:

    \[\ce{SO2Cl2 ⟶ SO2 + Cl2}\]

    Time (s) 0 5.00 × 103 1.00 × 104 1.50 × 104 2.50 × 104 3.00 × 104 4.00 × 104
    [SO2Cl2] (M) 0.100 0.0896 0.0802 0.0719 0.0577 0.0517 0.0415

    Q3.7

    Some bacteria are resistant to the antibiotic penicillin because they produce penicillinase, an enzyme with a molecular weight of 3 × 104 g/mol that converts penicillin into inactive molecules. Although the kinetics of enzyme-catalyzed reactions can be complex, at low concentrations this reaction can be described by a rate equation that is first order in the catalyst (penicillinase) and that also involves the concentration of penicillin. From the following data: 1.0 L of a solution containing 0.15 µg (0.15 × 10−6 g) of penicillinase, determine the order of the reaction with respect to penicillin and the value of the rate constant.

     
    [Penicillin] (M) Rate (mol/L/min)
    2.0 × 10−6 1.0 × 10−10
    3.0 × 10−6 1.5 × 10−10
    4.0 × 10−6 2.0 × 10−10