At a certain fixed temperature, the reaction A(g) + 2 B(g) → AB2(g) is found to be first order in the concentration of A and zero order in the concentration of B. The reaction rate constant is 0.0672 s−1 . If 2.000 moles of A and 4.000 moles of B are placed in a 1.000 liter container, how many seconds will elapse before the concentration of A has fallen to 0.300 mol/liter? 1. 36.6948 2. 60.226 3. 63.2373 4. 34.244 5. 49.9242 6. 23.8631 7. 51.2735 8. 29.6425 9. 36.1356 10. 28.231 Answer in units of s.

28.231 seconds

Explanation:

Rate law says that rate of a reaction is directly proportional to the concentration of the reactants each raised to a stoichiometric coefficient determined experimentally called as order.

Thus overall order = 1

Expression for rate law for first order kinetics is given by:

where,

k = rate constant =

t = time taken for decomposition

a = initial amount of the reactant A =

a - x = amount left after decay process = 0.300 M

28.231 seconds will elapse before the concentration of A has fallen to 0.300 mol/liter