Ammonia decomposes at high temperature according to the reaction 2 NH₃(g) → N₂(g) + 3…
CHEMISTRY · Multi-part · CBSE · Chemistry · Chemical Kinetics · Chemical Kinetics
Problem
Ammonia decomposes at high temperature according to the reaction
2 NH₃(g) → N₂(g) + 3 H₂(g) (Reaction 2)
At 800 K, the decomposition is first order in NH₃. Two experiments were performed at this temperature with an initial [NH₃] of 0.0500 M:
• Experiment A: no catalyst present; the half-life t₁⁄₂ was measured to be 600 s.
• Experiment B: a metallic surface catalyst was introduced; the half-life was 80 s.
Assume ideal behavior and constant temperature.
(a) Calculate the rate constants k_A and k_B for Experiments A and B, respectively, using the half-life information for a first-order reaction.
(b) Determine by what factor the catalyst increases the rate constant.
(c) For Experiment B, compute the time required for 90.0 % of the initial ammonia to decompose.