Today, ammonia is synthesized through a series of reactions (called the Haber-Bosch process) that take place between methane, air (which is four parts N2, one part O2), and potassium carbonate: 7 CH4(g) + 8 N2(g) +2 O2(g) + 17 H2O(g) + 7 K2CO3(s) ⇀↽ 16 NH3(g) + 14 KHCO3(s) What is the equilibrium expression for the Harber-Bosch process?

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.