Question

Aqueous `AB_(2)` decomposes according to the first order reaction:
`AB_(2)(aq) rarr A(g) + 2B(l)`
After `20 min` the volume of `A(g) ` colledcted during such a reaction is `20 mL`, and that collected after a very long time is `40 mL`. The rate constant is :
A. `A. 3.45 xx 10^(-3) min^(-1)`
B. `B. 3.45 xx 10^(-2) min^(-1)`
C. `C. 1.435 xx 10^(-2) min^(-1)`
D. `D. 6.93 min^(-1)`

Answer 1

Correct Answer - B
`{:(,AB_(2)(aq) ,underset("first order")rarr,A(g),2B(l)),(t=0,a,,0,0),(t=20 min,(a-x),,x,2x),(t=oo min,0,,a,2a):}`
Note: At constant `T` and `P`, mole `prop` pressure.
`:. x prop 20`
`alpha prop 40`
`:. k = (2.3)/(t)log.((a)/(a-x))`
`= (2.3)/(20 min) log. (40)/((40-20))`
`= (2.3)/(20) xx log2 = (2.3 xx 0.3)/(20) = 3.45 xx 10^(-2) min^(-1)`