Data for the decomposition of hydrogen peroxide at some set temperature T is provided below. The rate law depends only on the concentration of H2O2. (These same data will be used for questions 6, 7 and 8.) 2 H2O2 ---> 2 H2O O2 t (seconds) 0 60 120 180 240 360 420 600 [H2O2] (M) 0.882 0.697 0.566 0.458 0.372 0.236 0.188 0.094 What is the value of the rate constant, k

Respuesta :

Answer:

[tex]0.00442 s^{-1}[/tex] is the value of the rate constant.

Explanation:

[tex]2 H_2O_2\rightarrow 2 H_2O + O_2[/tex]

Let the order of the reaction be x.

The rate law of the reaction can be written as:

[tex]R=k[H_2O_2]^x[/tex]

1. Rate of the reaction when concentration changes from 0.882 M to 0.697 M in 0 seconds  to 60 seconds.

[tex]R=-\frac{0.697 M-0.882 M}{60 s-0 s}=0.00308 M/s[/tex]

[tex]0.00308 M/s=k[0.697 M]^x[/tex]..[1]

2. Rate of the reaction when concentration changes from  0.697 M to 0.566 M in 240 seconds to 360 seconds.

[tex]R=-\frac{0.236M-0.372M}{120s-60 s}=0.00227 M/s[/tex]

[tex]0.00218 M/s=k[0.236 M]^x[/tex]..[2]

[1] ÷ [2]

[tex]\frac{0.00308 M/s}{0.00227 M/s}=\frac{k[0.697 M]^x}{k[0.236M]^x}[/tex]

Solving fro x:

x = 0.92 ≈ 1

[tex]R=k[H_2O_2]^1[/tex]

[tex]0.00308 M/s=k[0.697 M]^1[/tex]

[tex]k=\frac{0.00308 M/s}{[0.697 M]^1}=0.00442 s^{-1}[/tex]

[tex]0.00442 s^{-1}[/tex] is the value of the rate constant.

The value of the rate constant is 0.00442 [tex]s^{-1}[/tex]

Balanced chemical reaction:

[tex]H_2O_2 --- > 2 H_2O+O_2[/tex]

Calculation for rate constant:

Let the order of the reaction be x.

The rate law of the reaction can be written as:

Rate = [tex]k[H_2O_2]^x[/tex]

1. Rate of the reaction when concentration changes from 0.882 M to 0.697 M in 0 seconds  to 60 seconds.

[tex]R=-\frac{0697M-0.882 M}{60-0} \\\\R=0.00308M/s\\[/tex]

0.00308 M/s = [tex]k[0.697]^x[/tex]................(i)

2. Rate of the reaction when concentration changes from 0.697 M to 0.566 M in 240 seconds to 360 seconds.

[tex]R=-\frac{0.236M-0.372 M}{120-60} \\\\R=0.00227M/s\\[/tex]

0.00277 M/s = [tex]k[0.239]^x[/tex]................(ii)

On dividing ii by i

x = 0.92 ≈ 1

[tex]\text{Rate}=k[H_2O_2]^1\\\\0.00308=k[0.697]\\\\k=\frac{0.00308}{0.697} \\\\k=0.00442s^{-1}[/tex]

Thus, The value of the rate constant is 0.00442 [tex]s^{-1}[/tex]

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