Question

The decomposition of HBr(g) into elemental species is found to have a rate constant of 4.2 ×10⁻³atm s⁻¹.  If 2.00 atm of HBr are present initially, how many minutes must elapse to achieve complete conversion into elements (i.e. all HBr(g) is gone)?  Assume a completely one-way reaction.

Answer 1

Given,

The rate constant(k) of the decomposition of HBr(g) into elemental species = 4.2 x 10^-3 atm s^-1

Also given,

The initial pressure of HBr(g) = 2.00 atm

Thus, calculating the time required to achieve complete conversion,

= 2.00 atm x ( 1 s / 4.2 x 10^-3 atm)

= 476.2 seconds

Converting seconds to minutes,

= 476.2 seconds x ( 1 minute /60 seconds)

= 7.9 minutes [ 2 S.F]