Consider the following initial rate data (at 273 K) for the decomposition of a substrate (substrate 1) which decomposes to product 1 and product 2: [Substrate 1] (M) Initial Rate (M/s) 0.4 0.183 0.8 0.183 2 0.183 Determine the half-life for the decomposition of substrate 1 when the initial concentration of the substrate is 2.77 M.

Respuesta :

Answer:

15.1 seconds is the half life of the reaction when concentration of the substrate is 2.77 M.

Explanation:

A → B + C

The rate law of the reaction will be :

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

Initial rate of the reaction when concentration of the substrate was 0.4 M:

[tex]0.183 M/s=k[0.4 M]^x[/tex]..[1]

Initial rate of the reaction when concentration of the substrate was 0.8 M:

[tex]0.183 M/s=k[0.8 M]^x[/tex]...[2]

[1] ÷ [2] :

[tex]\frac{0.183 M/s}{0.183 M/s}=\frac{k[0.4 M]^x}{k[0.8 M]^x}[/tex]

x = 0

The order of the reaction is zero.

For the value of rate constant ,k:

[tex]0.183 M/s=k[0.4 M]^x[/tex]..[1]

x = 0

[tex]0.183 M/s=k[0.4 M]^0[/tex]

k= 0.183 M/s

The half life of the zero order kinetics is given by :

[tex]t_{1/2}=\frac{[A_o]}{2k}[/tex]

Where:

[tex][A_o][/tex] = Initial concentration of A

k = Rate constant of the reaction

So, the half-life for the decomposition of substrate 1 when the initial concentration of the substrate is 2.77 M:

[tex]t_{1/2}=\frac{2.77 M}{0.183 M/s}=15.1 s[/tex]

15.1 seconds is the half life of the reaction when concentration of the substrate is 2.77 M.