How do I solve this rate law problem on the decomposition of ammonia on a platinum surface at 856°C

Question

In the decomposition of ammonia on a platinum surface at 856°C

 

2NH3(g)+==>N2(g)+3H2 (g)

 

Changing the concentration of nh3 has no effect on the rate.

 How do I write the rate law?

Answer 1

Hi, you write a zero order rate law, where rate = k[NH3]^0 = k.

Answer 2

You should understand that since changing the [NH3] has no effect on rate, then it is zero order with respect to NH3.

Thus rate law would be rate = k