👌 IMPROVE: Add more exercises throughout the tutorial

[ramirezfranciscof]

From the 2020 virtual tutorial feedback:

There were some requests for more advanced material and exercises (with sidenotes that they understand this is a basic tutorial). I think this makes sense, this is why I wanted to make the final EquationOfState work chain an exercise. I also missed exercises when first going through the tutorial.

I would say it would benefit from both some more easy "replace" exercises during the explanation, and maybe some more involved advanced exercises at the end of each section (just before/after the section summary).

[mbercx]

Might be good to separate this issue into ones for each section/module, or make a checklist here. Let's do this once all the modules are in place.