Q. Hydrogen peroxide , H2O2(aq) decomposes to H2O (l) and O2 (g) in a

1.	Q. Hydrogen peroxide , H2O2(aq) decomposes to H2O (l) and O2 (g) in a reaction that is first order in H2O2and has a rate constant k= 1.06 X 10-3 min -1.(i) How long it will take 15 % of a sample of H2O2 to decompose ?(ii) How long it will take 85 % of a sample to decompose ?
Answer» ANSWER:i) 2.55 hours of time require to DECOMPOSE 15% of hydrogen peroxide sample. ii)29.83 hours of time require to decompose 85% of hydrogen peroxide sample. Explanation: The integrated expression of FIRST order reaction: $kt=2.303\log\frac{[A_o]}{[A]}$ [/tex] k = rate constant, [A] = concentration of sample at time t. $[A_o]$ = initial concentration $H_2O_2$ i) time taken 15 % of a sample of to decompose: $[A]=A_o-15\%[A_o]=0.85[A_o]$ $1.06\times 10^{-3} min^{-1}t=2.303\log\frac{[A_o]}{[0.85A_o]}$ $t_{15\%}=153.34 min=2.55 hours(1 hour=60 min)$ $H_2O_2$ ii) time taken 85 % of a sample of to decompose: $[A]=A_o-85\%[A_o]=0.15[A_o]$ $1.06\times 10^{-3} min^{-1}t=2.303\log\frac{[A_o]}{[0.15A_o]}$ $t_{15\%}=1790 min=29.83 hours$