Question

What is the rate constant k for the decomposition of N2O5 (g) to NO2(g) and O2(g) at 250°C if the initial concentration of N2O5 is 0.10 M and the half-life for the reaction is 120 seconds?

Answer 1

The decomposition of N2O5 can be represented by the following reaction:N2O5  g   2 NO2  g  + 1/2 O2  g Since the reaction is first-order, we can use the first-order half-life equation:t1/2 = 0.693 / kWhere t1/2 is the half-life and k is the rate constant.We are given the half-life  t1/2  as 120 seconds. We can now solve for the rate constant  k :120 s = 0.693 / kRearranging the equation to solve for k:k = 0.693 / 120 sk  0.005775 sSo, the rate constant k for the decomposition of N2O5 at 250C is approximately 0.005775 s.