When nitrogen and hydrogen mix, they don't form anything immediately. They remain as separate gases. However, under specific conditions, they can react to form ammonia (NH₃).

Here's the breakdown:

* Mixing: Nitrogen (N₂) and hydrogen (H₂) gases can be mixed together without reacting. They simply exist as separate molecules in the mixture.

* Reaction: To form ammonia, the mixture needs to be subjected to high pressure (around 200 atmospheres) and high temperature (around 450-550°C) in the presence of a catalyst (typically iron). This process is called the Haber-Bosch process.

* Product: The reaction combines one nitrogen molecule with three hydrogen molecules to produce two ammonia molecules:

N₂ + 3H₂ → 2NH₃

So, while a simple mixture of nitrogen and hydrogen is just that – a mixture – under specific conditions, they can react to form the very useful compound, ammonia.