Question

Consider a reaction `A(g) rarr 3B(g) + 2C(g)` with rate constant is `1.386 xx 10^(-2) "min"^(-1)` in a non-rigid closed container starting with `2` moles of `A` in `12.5 L` vessel initially, if reaction is allowed to take place at constant pressure and at `298 K` the conc. of after `100 min` is
A. `0.18 M`
B. `0.03 M`
C. `0.09 M`
D. `0.01 M`

Answer 1

Correct Answer - C
`A rarr 3B + 2C`
`K = (2.303)/(t) "log"([A]_(0))/([A])`
`rArr [A] = 0.0016`
`.0016 = (n_(A))/("Vol")`
`.0016 xx 12.5 = n_(A)`
`n_(A) = .02`
`x_(A)` decompsed `= 2 - 0.02`
`= 198`.
Moles of `A` decomposed `= 1.98`
So moles of `B` formed `= 5.94`
Assuming `n prop v` final vol. `= 62 L`
So fins conc. of `B = (5.94)/(62) = 0.09 mol//L`.