The decomposition of ammonia to nitrogen and hydrogen on a tungsten filament at 800°C is independent of the concentration of ammonia at high pressures of ammonia. What is the order of the reaction with respect to ammonia?

Order zero

Explanation:

Let's consider the decomposition of ammonia to nitrogen and hydrogen on a tungsten filament at 800°C.

2 NH₃ (g) → N₂ (g) + 3 H₂ (g)

The generic rate law is:

rate = k * [NH₃]ⁿ

where,

rate: reaction rate

k: rate constant

n: reaction order

When n = 0, we get:

rate = k * [NH₃]⁰ = k

As we can see, when the reaction order with respect to ammonia is zero, the reaction rate is independent of the concentration of ammonia.