@jxself I find your reasoning more persuasive than any of the LLMs that were consulted so far:
https://mstdn.io/@codewiz/113711484285996319
Your formula gives 369g/L, a bit more than Copilot's 275g/L and ChatGPT's 286g/L.
But where is the mistake in their process? The calculations and the atomic weights look correct.