Question

At a certain temperature the rate of this reaction is second order in NH_3 with a rate constant of 0.100 M^-1 middot s^-1 2NH_3 g) rightarrow N_2 (g) + 3H_2 (g) Suppose a vessel contains NH_3 at a concentration of 0.960 M. Calculate how long it takes for the concentration of NH_3 to decrease to 0.134 M. You may assume no other reaction is important. Round your answer to significant digits.

Answer 1

second order reaction

K = x/t(a0-x)a0

K = rate constant = 0.1 M-1.S-1

a0 = initial concentration of NH3 = 0.96 M

a = a0-x = concentration of NH3 after t sec = 0.134 M

x = change in concentration = 0.96 - 0.134 = 0.826 M

0.1 = 0.826/(t*0.134*0.96)

t = time = 6.4*10^1 sec