Update: Based on the lively discussion here, there is now a featured meta post where you can propose specific changes.
When users ask their first question, they now are shown the following information (to see this, log out or open a private browser window and go to https://chemistry.stackexchange.com/questions/ask):
To give an example of what another site did, below is the modified information from Code Golf, which they requested after discussing it on their meta.
Physics mentions homework-like questions not on the "first-question" prompt but always as step 1 of asking a question:
In contrast, our step 1 directions are much shorter and without links (maybe some of the physics language could go into the "first-question" box, or into the step 1 side-bar):
How could we customize our prompt (or anything in the help center) to address some of the typical shortcomings of first questions (and how could we test whether it had an impact)?