chEEmystery
If screened methyl orange’s transition pH range is 3.8-4.1, why are we using it for, say, standardising hydrochloric acid with standard aq sodium carbonate? I think I’m missing something here.
Besides, as far as I can tell, there’s no IBO restriction on indicators for IAs: why can’t we use phenolphthalein (transition pH range of 8.2-10.0) which our secondary chem teachers have been enlightened enough to use for practicals? I don’t see how it’d affect the assessment criteria, ceteris paribus (haha, I know, blatant abuse of the term and all). Phenolphthalein would certainly be less ambiguous than the nearly arbitrary greyish-green/greyish-purple endpoint of screened methyl orange.
Anyway, whatever. I just want to finish my Chem IA3 tonight so that I can leave the next 3 evenings for the English written commentary on Anthem, Chinese movie review, and Math revision/assignments. It’d feel good having settled Chem and most of Chinese today, despite the photographical distractions.
