Ammonia decomposes on the surface of hot tungsten metal.
2NH3(g) → N2(g) + 3H2(g)
The reaction happens only when ammonia molecules are attached to sites on the tungsten surface. The graph shows how the concentration of ammonia changed with time at constant temperature.
Deduce the order of reaction with respect to ammonia. Explain how the graph shows this.
[2]
Write the rate equation for this reaction.
[1]
Calculate the value of the rate constant, k, and give its units.
[3]
Suggest why the rate does not depend on the concentration of ammonia under these conditions.
[2]