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# Homework 3 (Due 4/11/16)

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 5 10 15 20 25 35 [A] (M) 1 0.952 0.625 0.465 0.37 0.308 0.23
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) 0.1 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