Yesterday, some people were encouraging me to convert to using atomic species balance to do mass balance, because it's the easiest method. I kinda disagree, since my mind automatically jumps to extent of reaction when I look at a mass balance question.

The thing about atomic species balance is that it is just SO reductionistic! It reduces reactions into abstract components (a.k.a atoms) and disregards the nature of the reaction in its calculations. It's kinda like saying, 'a painting is a lot of chemicals on a piece of paper'. It's true, but it does not really describe to us what a painting is. Similarly, i think atomic species balance does not provide a good feel of what is happening in a reaction, unlike extent of reaction.

(Let us, for the sake of simplicity, ignore the fact that there are now more ways to make a painting other than spreading chemicals on a piece of paper.)

I think I'm probably just bitter about losing 2 marks to a failed degree-of-freedom analysis. Haha.