I'd like to know how and what chemical if any, do i need to scrape my stucco bedroom ceiling so i can get it to a plain, smooth type white ceiling
A true "stucco" is made of cement and will be very difficult to scrape clean. Sometimes what may look like "stucco" is in fact a drywall compound that is applied like a stucco finish. If this is the case then directly sanding the surface down with a reduction of heavy-to-light grit sand paper will work.
In my experience, I have found that applying a couple skim coats of drywall compound directly over the surface and then sanding to smooth - is a more direct way to achieve your goal. Prime and paint when finished.