<p>For Chem 21L, The required book is Chang Chemistry, 9th edition, which runs $141 used on the Duke bookstore site. However, I took ap chem in high school and I own the Chang Chemistry 7th edition. Can I use that one or do I have to buy a new one? Thanks so much!</p>
<p>anyone? im trying to pack right now so an answer would be greatly appreciated- thanks!</p>
<p>I don't think you can use older editions. The problem sets would probably be different in each chapter, and the book overall would just be older and not as up to date.</p>