2 C2H6 + 7 O2 → 6 H2O + 4 CO2 If 5.25 moles of ethane (C2H6) and 15.0 moles of oxygen are reacted, which is the limiting reactant? How many moles of water would be made?

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.

that's what i got you can count the number of atoms