Can I bleach pastel yellow 100% cotton curtains white?

Get a very large pot, fill it half way, put about 1/3 cup of bleach in, not so much that it will tear your sheets, just enough to get the point across to your curtains that they're gonna get a makeover, boil the water and bleach mixture and once it's to a boil, put your curtains in, turn to medium so that it's not going to boil over but still have a slight boil/heavy simmer, stir every 10 minutes with a wooden spoon, redo that if it doesn't work with a little more bleach, but definitely don't over do it with the bleach because you could tear the curtains so be easy with the bleach but not scared of it either, maybe 1/4 cup bleach to every 2 1/2 cups water.