Answer:
[tex]t=90.0s[/tex]
Explanation:
Hello,
In this case, for first-order kinetics we have an integrated rate law of this reaction as:
[tex]ln(\frac{[N_2O_5]}{[N_2O_5]_0} )=-kt[/tex]
Thus, we compute the time for an initial concentration of 0.280 M which ends up in 0.0476 M as shown below:
[tex]t=\frac{ln(\frac{[N_2O_5]}{[N_2O_5]_0} )}{-k}=\frac{ln(\frac{0.0476M}{0.280M})}{-0.0197s}\\ \\t=90.0s[/tex]
Best regards.