contestada

N2O5(g) → NO3(g) + NO2(g)
This reaction is 1st order with half-life = 18.0 seconds. How long will it take for 95% of a sample of N2O5(g) to react?

A. 42.2 seconds
B. 132 seconds
C. 109 seconds
D. 77.8 seconds
E. 158 seconds

Respuesta :

Answer:

It will take 77.8 seconds for 95% of sample to react

Explanation:

As the given reaction obeys 1st order therefore-

                        [tex][N_{2}O_{5}]=[N_{2}O_{5}]_{0}\times (\frac{1}{2})^{\frac{t}{t_{\frac{1}{2}}}}[/tex]

Where [tex][N_{2}O_{5}][/tex] is the concentration of [tex]N_{2}O_{5}[/tex] after "t" time, [tex][N_{2}O_{5}]_{0}[/tex] is the initial concentration of [tex]N_{2}O_{5}[/tex] and [tex]t_{\frac{1}{2}}[/tex] is half life

Here, [tex]\frac{[N_{2}O_{5}]}{[N_{2}O_{5}]_{0}}=\frac{100-95}{100}=0.05[/tex] and [tex]t_{\frac{1}{2}}=18.0 seconds[/tex]

So, [tex]0.05=(\frac{1}{2})^{\frac{t}{18.0seconds}}[/tex]

or, [tex]t=77.8 seconds[/tex]

So, it will take 77.8 seconds for 95% of sample to react

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