A common assumption writers make is that that and which are interchangeable. They are not. That is a defining or restrictive pronoun, which means that the information following it is necessary for the sentence to make sense. Which is a nondefining, or nonrestrictive pronoun, which means that the text following it adds information that is not necessary for the sentence to make sense.
Compare the following sentences:
The book that John wrote is a bestseller.
(Indicates which book.)
The book, which John wrote, is a bestseller.
(Adds a fact about the book in question.)
Go on a which-hunt to make your manuscript as error free as possible before you submit it. Here’s a quick test you can use:
Pull out the clause that begins with either that or which, and then read your sentence. Did the omission make the sentence unclear or change its meaning? If so, you should use that. If not, go with which. Check it out:
Please hand me the bowl that my mom gave me.
I’m going use the bowl, which my mom gave me, to serve a salad.
I constantly misused THAT and WHICH in my book’s text.
My copy editor was generally unhelpful. The transposition of that and which was the only one of her changes that I kept.