I picked up penicillin from the pharmacy. When my young kid asked me what this is, I said that's C16H18N2O5S and gave them a chemistry book to read. Next day, I found these two puzzles on my desk:
N: chromium nitrate, no water
W: carbonyl sulfide & tin telluride; caesium astatide & calcium selenide & beryllium oxide; rubidium iodide & sodium chloride
I started getting a headache and was about to go to the pharmacy again for some C9H8O4 tablets, also known as aspirin. But then I managed to solve the puzzle without medical help and I realized those coordinates are within a short walk from that pharmacy.