Using the same experimental protocol, the density lookup ability of GPT-4 shows 100% accuracy in 5 conversations that specifically requested density lookups. Although GPT-4 was demonstrated to have great understand of chemical information including molecular weight, the lookup results in prompt 1 cannot output the correct molecular weight for 5,6dichloropyrazine-2,3-dicarbonitrile in all 10 conversations, resulting the incorrect mass output even though using the correct equation (ESI † Table ). This error may stem from incorrect formula identification and a lack of chemistry knowledge, as GPT-4 did not activate web browsing feature, possibly related to recent cases of web searching reluctancy. However, this can be fixed by prompting "search the molecular weight" and/or providing the chemical formula to leverage general chemistry knowledge. Additionally, an external chemical database embedding can also enhance the lookup accuracy.